diff --git a/.github/workflows/java-cloud-bom-ci.yaml b/.github/workflows/java-cloud-bom-ci.yaml
index 3e83cf926698..5ccf37d4327d 100644
--- a/.github/workflows/java-cloud-bom-ci.yaml
+++ b/.github/workflows/java-cloud-bom-ci.yaml
@@ -59,6 +59,8 @@ jobs:
         java-version: ${{matrix.java}}
         cache: 'maven'
     - run: java -version
+    - name: Use GCP Maven Mirror
+      run: mkdir -p "${HOME}/.m2" && cp settings.xml "${HOME}/.m2/settings.xml"
     - name: Install modules locally
       run: mvn install -B -ntp -Pquick-build -DskipTests=true -T 1C
     - run: .kokoro/dependencies.sh
@@ -77,6 +79,8 @@ jobs:
         java-version: 11
         cache: maven
     - run: java -version
+    - name: Use GCP Maven Mirror
+      run: mkdir -p "${HOME}/.m2" && cp settings.xml "${HOME}/.m2/settings.xml"
     - name: Install modules locally
       run: mvn install -B -ntp -Pquick-build -DskipTests=true -T 1C
     - name: Install BOMs
@@ -107,6 +111,8 @@ jobs:
         java-version: 11
         cache: maven
     - run: java -version
+    - name: Use GCP Maven Mirror
+      run: mkdir -p "${HOME}/.m2" && cp settings.xml "${HOME}/.m2/settings.xml"
     - name: Install modules locally
       run: mvn install -B -ntp -Pquick-build -DskipTests=true -T 1C
     - name: Install BOMs
diff --git a/.github/workflows/java-cloud-bom-release-note-generation.yaml b/.github/workflows/java-cloud-bom-release-note-generation.yaml
index d8ed304490f9..51f7f277f97b 100644
--- a/.github/workflows/java-cloud-bom-release-note-generation.yaml
+++ b/.github/workflows/java-cloud-bom-release-note-generation.yaml
@@ -34,6 +34,8 @@ jobs:
         java-version: 11
         cache: maven
     - run: java -version
+    - name: Use GCP Maven Mirror
+      run: mkdir -p "${HOME}/.m2" && cp settings.xml "${HOME}/.m2/settings.xml"
     - name: Install modules locally
       run: mvn install -B -ntp -Pquick-build -DskipTests=true -T 1C
     - name: Pick Libraries BOM version
diff --git a/.github/workflows/java-spanner-jdbc-quickperf.yaml b/.github/workflows/java-spanner-jdbc-quickperf.yaml
index 853d136e098a..666da5ecd53c 100644
--- a/.github/workflows/java-spanner-jdbc-quickperf.yaml
+++ b/.github/workflows/java-spanner-jdbc-quickperf.yaml
@@ -49,6 +49,8 @@ jobs:
           distribution: temurin
           java-version: 17
           cache: maven
+      - name: Use GCP Maven Mirror
+        run: mkdir -p "${HOME}/.m2" && cp settings.xml "${HOME}/.m2/settings.xml"
       - name: Run tests
         run: mvn test
         working-directory: java-spanner-jdbc/samples/quickperf
diff --git a/.github/workflows/java-spanner-jdbc-sample-tests.yml b/.github/workflows/java-spanner-jdbc-sample-tests.yml
index 37533f87e8b5..d71db1da766d 100644
--- a/.github/workflows/java-spanner-jdbc-sample-tests.yml
+++ b/.github/workflows/java-spanner-jdbc-sample-tests.yml
@@ -49,6 +49,8 @@ jobs:
           distribution: temurin
           java-version: 8
           cache: maven
+      - name: Use GCP Maven Mirror
+        run: mkdir -p "${HOME}/.m2" && cp settings.xml "${HOME}/.m2/settings.xml"
       - name: Run sample tests
         run: mvn --quiet --batch-mode test
         working-directory: java-spanner-jdbc/samples/snippets
diff --git a/.github/workflows/java-spanner-jdbc-spring-data-jdbc-sample.yaml b/.github/workflows/java-spanner-jdbc-spring-data-jdbc-sample.yaml
index 761f8fbcd8db..0fc27d18ee32 100644
--- a/.github/workflows/java-spanner-jdbc-spring-data-jdbc-sample.yaml
+++ b/.github/workflows/java-spanner-jdbc-spring-data-jdbc-sample.yaml
@@ -49,6 +49,8 @@ jobs:
           distribution: temurin
           java-version: 17
           cache: maven
+      - name: Use GCP Maven Mirror
+        run: mkdir -p "${HOME}/.m2" && cp settings.xml "${HOME}/.m2/settings.xml"
       - name: Run tests on GoogleSQL
         run: mvn test
         working-directory: java-spanner-jdbc/samples/spring-data-jdbc/googlesql
diff --git a/.github/workflows/java-spanner-jdbc-spring-data-mybatis-sample.yaml b/.github/workflows/java-spanner-jdbc-spring-data-mybatis-sample.yaml
index ce85b6b59dfa..ab6c6a66db85 100644
--- a/.github/workflows/java-spanner-jdbc-spring-data-mybatis-sample.yaml
+++ b/.github/workflows/java-spanner-jdbc-spring-data-mybatis-sample.yaml
@@ -49,6 +49,8 @@ jobs:
           distribution: temurin
           java-version: 17
           cache: maven
+      - name: Use GCP Maven Mirror
+        run: mkdir -p "${HOME}/.m2" && cp settings.xml "${HOME}/.m2/settings.xml"
       - name: Run GoogleSQL sample tests
         run: mvn test
         working-directory: java-spanner-jdbc/samples/spring-data-mybatis/googlesql
diff --git a/.github/workflows/sdk-platform-java-analyze_dependency.yaml b/.github/workflows/sdk-platform-java-analyze_dependency.yaml
index 12d8f926a688..95bfd20cf775 100644
--- a/.github/workflows/sdk-platform-java-analyze_dependency.yaml
+++ b/.github/workflows/sdk-platform-java-analyze_dependency.yaml
@@ -54,6 +54,8 @@ jobs:
       uses: stCarolas/setup-maven@07fbbe97d97ef44336b7382563d66743297e442f # v4.5
       with:
         maven-version: 3.8.2
+    - name: Use GCP Maven Mirror
+      run: mkdir -p "${HOME}/.m2" && cp settings.xml "${HOME}/.m2/settings.xml"
     - name: Install dependency analyzer
       shell: bash
       run: |
diff --git a/.github/workflows/sdk-platform-java-downstream_protobuf_compatibility_check_nightly.yaml b/.github/workflows/sdk-platform-java-downstream_protobuf_compatibility_check_nightly.yaml
index fa65b5b92603..c6631fc64a16 100644
--- a/.github/workflows/sdk-platform-java-downstream_protobuf_compatibility_check_nightly.yaml
+++ b/.github/workflows/sdk-platform-java-downstream_protobuf_compatibility_check_nightly.yaml
@@ -34,6 +34,8 @@ jobs:
           java-version: 11
           distribution: temurin
           cache: maven
+      - name: Use GCP Maven Mirror
+        run: mkdir -p "${HOME}/.m2" && cp settings.xml "${HOME}/.m2/settings.xml"
       - id: resolve-versions
         name: Resolve Protobuf versions
         env:
diff --git a/.github/workflows/sdk-platform-java-shared_dependencies.yaml b/.github/workflows/sdk-platform-java-shared_dependencies.yaml
index d6bed662aecd..d955f1712e09 100644
--- a/.github/workflows/sdk-platform-java-shared_dependencies.yaml
+++ b/.github/workflows/sdk-platform-java-shared_dependencies.yaml
@@ -43,6 +43,8 @@ jobs:
         java-version: 17
         cache: maven
     - run: java -version
+    - name: Use GCP Maven Mirror
+      run: mkdir -p "${HOME}/.m2" && cp settings.xml "${HOME}/.m2/settings.xml"
     - name: Install maven modules
       run: |
         mvn install -B -ntp -DskipTests -Pquick-build
diff --git a/.github/workflows/unmanaged_dependency_check.yaml b/.github/workflows/unmanaged_dependency_check.yaml
index c7811ef89381..d647d4dca070 100644
--- a/.github/workflows/unmanaged_dependency_check.yaml
+++ b/.github/workflows/unmanaged_dependency_check.yaml
@@ -38,6 +38,8 @@ jobs:
           distribution: temurin
           java-version: 11
           cache: maven
+      - name: Use GCP Maven Mirror
+        run: mkdir -p "${HOME}/.m2" && cp settings.xml "${HOME}/.m2/settings.xml"
       - name: Install all modules
         shell: bash
         run: |
diff --git a/.kokoro/bigtable-conformance.sh b/.kokoro/bigtable-conformance.sh
index 038cbfc75249..21ba354f5087 100755
--- a/.kokoro/bigtable-conformance.sh
+++ b/.kokoro/bigtable-conformance.sh
@@ -22,6 +22,7 @@ cd ${scriptDir}/..
 
 # include common functions
 source ${scriptDir}/common.sh
+setup_maven_mirror
 
 # Print out Maven & Java version
 mvn -version
diff --git a/.kokoro/build.sh b/.kokoro/build.sh
index 92e714cb451e..5632bfe49329 100755
--- a/.kokoro/build.sh
+++ b/.kokoro/build.sh
@@ -22,10 +22,7 @@ cd ${scriptDir}/..
 
 # include common functions
 source ${scriptDir}/common.sh
-
-# Use GCP Maven Mirror
-mkdir -p ${HOME}/.m2
-cp settings.xml ${HOME}/.m2
+setup_maven_mirror
 
 setup_application_credentials
 
diff --git a/.kokoro/client-library-check-doclet.sh b/.kokoro/client-library-check-doclet.sh
index 3c774c62582f..812a26548953 100755
--- a/.kokoro/client-library-check-doclet.sh
+++ b/.kokoro/client-library-check-doclet.sh
@@ -75,6 +75,10 @@ scriptDir=$(realpath $(dirname "${BASH_SOURCE[0]}"))
 ## cd to the parent directory, i.e. the root of the git repo
 cd ${scriptDir}/..
 
+# include common functions
+source ${scriptDir}/common.sh
+setup_maven_mirror
+
 # Make artifacts available for 'mvn validate' at the bottom
 pushd java-shared-config
 mvn install -DskipTests=true -Dmaven.javadoc.skip=true -Dgcloud.download.skip=true -B -V -q --no-transfer-progress
diff --git a/.kokoro/client-library-check.sh b/.kokoro/client-library-check.sh
index 0eb9f817bb61..52d0d19d9b80 100755
--- a/.kokoro/client-library-check.sh
+++ b/.kokoro/client-library-check.sh
@@ -86,6 +86,10 @@ scriptDir=$(realpath $(dirname "${BASH_SOURCE[0]}"))
 ## cd to the parent directory, i.e. the root of the git repo
 cd ${scriptDir}/..
 
+# include common functions
+source ${scriptDir}/common.sh
+setup_maven_mirror
+
 # Make artifacts available for 'mvn validate' at the bottom
 pushd java-shared-config
 mvn install -DskipTests=true -Dmaven.javadoc.skip=true -Dgcloud.download.skip=true -B -V -q
diff --git a/.kokoro/common.sh b/.kokoro/common.sh
index 9a56b378131a..d942dca10449 100644
--- a/.kokoro/common.sh
+++ b/.kokoro/common.sh
@@ -564,15 +564,15 @@ function find_last_release_version {
   echo "${parts[1]}"
 }
 
-# copies settings.xml from the root of sdk-platform-java into Maven's home
-# folder
+# copies settings.xml from the root of the repo into Maven's home folder
 function setup_maven_mirror {
   echo "Setup maven mirror"
   mkdir -p "${HOME}/.m2"
-  cp "${commonScriptDir}/../settings.xml" "${HOME}/.m2"
+  cp "${commonScriptDir}/../settings.xml" "${HOME}/.m2/settings.xml"
 }
 
 function install_repo_modules {
+  setup_maven_mirror
   target_projects="$1"
   projects_arg=""
   if [ -n "${target_projects}" ]; then
diff --git a/.kokoro/dashboard.sh b/.kokoro/dashboard.sh
index 0a7fb642eb53..0b4803b4bbe4 100755
--- a/.kokoro/dashboard.sh
+++ b/.kokoro/dashboard.sh
@@ -18,6 +18,10 @@ set -eo pipefail
 scriptDir=$(realpath $(dirname "${BASH_SOURCE[0]}"))
 cd ${scriptDir}/..
 
+# include common functions
+source ${scriptDir}/common.sh
+setup_maven_mirror
+
 outputFile="$scriptDir/../java-cloud-bom/dashboard/target/tmp/output.txt"
 
 if [[ "${JOB_TYPE}" == "dashboard-units-check" ]]; then
diff --git a/.kokoro/dependencies.sh b/.kokoro/dependencies.sh
index f341016b5033..879157ffe96d 100755
--- a/.kokoro/dependencies.sh
+++ b/.kokoro/dependencies.sh
@@ -23,6 +23,7 @@ cd ${scriptDir}/..
 
 # include common functions
 source ${scriptDir}/common.sh
+setup_maven_mirror
 
 # Print out Java
 java -version
diff --git a/.kokoro/presubmit/downstream-build.sh b/.kokoro/presubmit/downstream-build.sh
index aa6781b1ffee..c3000d6b8866 100755
--- a/.kokoro/presubmit/downstream-build.sh
+++ b/.kokoro/presubmit/downstream-build.sh
@@ -31,6 +31,10 @@ scriptDir=$(realpath "$(dirname "${BASH_SOURCE[0]}")")
 ## cd to the parent directory, i.e. the root of the git repo
 cd "${scriptDir}/../.."
 
+# include common functions
+source "${scriptDir}/../common.sh"
+setup_maven_mirror
+
 # Build and install the entire monorepo to local cache (including the under-test java-shared-config)
 mvn -B -ntp install -Dcheckstyle.skip -Dfmt.skip -DskipTests
 
@@ -38,10 +42,6 @@ mvn -B -ntp install -Dcheckstyle.skip -Dfmt.skip -DskipTests
 VERSION_POM=java-shared-config/java-shared-config/pom.xml
 SHARED_CONFIG_VERSION=$(sed -e 's/xmlns=".*"//' ${VERSION_POM} | xmllint --xpath '/project/version/text()' -)
 
-# Use GCP Maven Mirror (as in original script)
-mkdir -p "${HOME}/.m2"
-cp java-shared-config/settings.xml "${HOME}/.m2"
-
 # Update the shared-config version in the local java-showcase parent
 pushd java-showcase
 modify_shared_config
diff --git a/java-shared-config/settings.xml b/java-shared-config/settings.xml
deleted file mode 100644
index 5df3ab0b2a1a..000000000000
--- a/java-shared-config/settings.xml
+++ /dev/null
@@ -1,23 +0,0 @@
-<!--
-  ~ Copyright 2023 Google LLC.
-  ~
-  ~ Licensed under the Apache License, Version 2.0 (the "License");
-  ~ you may not use this file except in compliance with the License.
-  ~ You may obtain a copy of the License at
-  ~
-  ~     http://www.apache.org/licenses/LICENSE-2.0
-  ~
-  ~ Unless required by applicable law or agreed to in writing, software
-  ~ distributed under the License is distributed on an "AS IS" BASIS,
-  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-  ~ See the License for the specific language governing permissions and
-  ~ limitations under the License.
-  -->
-
-<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"
-          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-          xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0
-                          https://maven.apache.org/xsd/settings-1.0.0.xsd">
-    <mirrors>
-    </mirrors>
-</settings>
\ No newline at end of file
diff --git a/sdk-platform-java/.kokoro/nightly/downstream-protobuf-binary-compatibility.sh b/sdk-platform-java/.kokoro/nightly/downstream-protobuf-binary-compatibility.sh
index 352b2dd9e24d..dde6da6c66af 100755
--- a/sdk-platform-java/.kokoro/nightly/downstream-protobuf-binary-compatibility.sh
+++ b/sdk-platform-java/.kokoro/nightly/downstream-protobuf-binary-compatibility.sh
@@ -22,6 +22,10 @@ validate_protobuf_compatibility_script_inputs
 
 monorepoRoot=$(realpath "${scriptDir}/../../..")
 
+# Use GCP Maven Mirror from monorepo root
+mkdir -p "${HOME}/.m2"
+cp "${monorepoRoot}/settings.xml" "${HOME}/.m2/settings.xml"
+
 # Declare a map of downstream handwritten libraries and the relevant artifacts to test. The map stores a
 # K/V pairing of (Key: module name, Value: comma separate list of Group ID:Artifact ID pairings). Note: The
 # value list doesn't hold the version and this needs to be parsed from the monorepo's versions.txt file
diff --git a/sdk-platform-java/.kokoro/nightly/downstream-protobuf-source-compatibility.sh b/sdk-platform-java/.kokoro/nightly/downstream-protobuf-source-compatibility.sh
index 5328e052e0eb..57e7fac0e2e1 100755
--- a/sdk-platform-java/.kokoro/nightly/downstream-protobuf-source-compatibility.sh
+++ b/sdk-platform-java/.kokoro/nightly/downstream-protobuf-source-compatibility.sh
@@ -22,6 +22,10 @@ validate_protobuf_compatibility_script_inputs
 
 monorepoRoot=$(realpath "${scriptDir}/../../..")
 
+# Use GCP Maven Mirror from monorepo root
+mkdir -p "${HOME}/.m2"
+cp "${monorepoRoot}/settings.xml" "${HOME}/.m2/settings.xml"
+
 # MODULES_UNDER_TEST Env Var accepts a comma separated list of monorepo submodules to test. For Github CI,
 # this will be a single module as Github will build a matrix of modules with each being tested in parallel.
 # For local invocation, you can pass a list of modules to test multiple modules together.
diff --git a/sdk-platform-java/.kokoro/presubmit/common.sh b/sdk-platform-java/.kokoro/presubmit/common.sh
index c9fd49ed299d..ea8884cf6ea3 100644
--- a/sdk-platform-java/.kokoro/presubmit/common.sh
+++ b/sdk-platform-java/.kokoro/presubmit/common.sh
@@ -92,15 +92,15 @@ function find_last_release_version {
   echo "${parts[1]}"
 }
 
-# copies settings.xml from the root of sdk-platform-java into Maven's home
-# folder
+# copies settings.xml from the root of the monorepo into Maven's home folder
 function setup_maven_mirror {
   echo "Setup maven mirror"
   mkdir -p "${HOME}/.m2"
-  cp "${commonScriptDir}/../../settings.xml" "${HOME}/.m2"
+  cp "${commonScriptDir}/../../../settings.xml" "${HOME}/.m2/settings.xml"
 }
 
 function install_repo_modules {
+  setup_maven_mirror
   target_projects="$1"
   projects_arg=""
   if [ -n "${target_projects}" ]; then
diff --git a/sdk-platform-java/.kokoro/presubmit/downstream-build.sh b/sdk-platform-java/.kokoro/presubmit/downstream-build.sh
index 3a093c876718..f16db5f52b5e 100755
--- a/sdk-platform-java/.kokoro/presubmit/downstream-build.sh
+++ b/sdk-platform-java/.kokoro/presubmit/downstream-build.sh
@@ -24,6 +24,7 @@ fi
 scriptDir=$(realpath "$(dirname "${BASH_SOURCE[0]}")")
 cd "${scriptDir}/../.." # git repo root
 source "$scriptDir/common.sh"
+setup_maven_mirror
 
 # Publish this repo's modules to local maven to make them available for downstream libraries
 mvn install --projects '!gapic-generator-java' \
diff --git a/sdk-platform-java/.kokoro/presubmit/showcase-native.sh b/sdk-platform-java/.kokoro/presubmit/showcase-native.sh
index ad85d8dc6a08..c44d60ed100b 100644
--- a/sdk-platform-java/.kokoro/presubmit/showcase-native.sh
+++ b/sdk-platform-java/.kokoro/presubmit/showcase-native.sh
@@ -21,8 +21,7 @@ cd "${scriptDir}/../.." # git repo root
 source "$scriptDir/common.sh"
 
 # Use GCP Maven Mirror
-mkdir -p "${HOME}/.m2"
-cp settings.xml "${HOME}/.m2"
+setup_maven_mirror
 
 # Publish this repo's modules to local maven to make them available for downstream libraries
 mvn install --projects '!gapic-generator-java' \
diff --git a/settings.xml b/settings.xml
index 3af27a94af88..1efe90bb814f 100644
--- a/settings.xml
+++ b/settings.xml
@@ -18,7 +18,60 @@
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0
                           https://maven.apache.org/xsd/settings-1.0.0.xsd">
-  <!-- This file contains settings used by .kokoro/build.sh. These are global
-   configs used by almost every build script.
+  <!--
+    Why we use an active <profile> with <repositories> instead of <mirrors>:
+
+    1. Exclusive Proxy Limitation of <mirrors>:
+       In Maven, a <mirrorOf> tag acts as an exclusive 1:1 replacement/proxy for a repository.
+       If an artifact returns 404 from the mirror (e.g. due to replication lag for brand-new
+       releases published to Maven Central minutes ago), Maven treats Central as exhausted
+       and immediately fails the build without querying Central root.
+
+    2. Prioritized Search Chain with Automatic Fallback:
+       By declaring the Google Cloud Storage mirror inside an active <profile> as a <repository>
+       and <pluginRepository>, Maven prepends the GCS mirror to its search list ahead of the
+       built-in Super POM's 'central' repository:
+         1. Local cache & reactor (~/.m2/repository)
+         2. 'google-maven-central' (GCS CDN mirror, serving ~99% of requests without 429 rate limits)
+         3. 'central' (https://repo.maven.apache.org/maven2 - queried automatically if missing from GCS)
+
+    3. settings.xml Schema Requirement:
+       In Maven's settings.xml specification, <repositories> cannot be declared directly at
+       the root <settings> level and must reside within <profiles><profile>. The <activeProfiles>
+       block below ensures this profile is unconditionally active for every build.
   -->
+  <profiles>
+    <profile>
+      <id>google-maven-mirror</id>
+      <repositories>
+        <repository>
+          <id>google-maven-central</id>
+          <name>Google Maven Central Mirror</name>
+          <url>https://maven-central.storage-download.googleapis.com/maven2/</url>
+          <releases>
+            <enabled>true</enabled>
+          </releases>
+          <snapshots>
+            <enabled>false</enabled>
+          </snapshots>
+        </repository>
+      </repositories>
+      <pluginRepositories>
+        <pluginRepository>
+          <id>google-maven-central</id>
+          <name>Google Maven Central Mirror</name>
+          <url>https://maven-central.storage-download.googleapis.com/maven2/</url>
+          <releases>
+            <enabled>true</enabled>
+          </releases>
+          <snapshots>
+            <enabled>false</enabled>
+          </snapshots>
+        </pluginRepository>
+      </pluginRepositories>
+    </profile>
+  </profiles>
+  <activeProfiles>
+    <activeProfile>google-maven-mirror</activeProfile>
+  </activeProfiles>
 </settings>