diff --git a/packages/network-enablement-controller/CHANGELOG.md b/packages/network-enablement-controller/CHANGELOG.md
index 5bd6f6d763..512e41c2e8 100644
--- a/packages/network-enablement-controller/CHANGELOG.md
+++ b/packages/network-enablement-controller/CHANGELOG.md
@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- Add Monad mainnet (`0x8f`, chain ID 143) to the default enabled network map ([#8743](https://github.com/MetaMask/core/pull/8743))
 - Bump `@metamask/transaction-controller` from `^65.0.0` to `^65.2.0` ([#8691](https://github.com/MetaMask/core/pull/8691), [#8722](https://github.com/MetaMask/core/pull/8722))
 
 ## [5.1.0]
diff --git a/packages/network-enablement-controller/src/NetworkEnablementController.test.ts b/packages/network-enablement-controller/src/NetworkEnablementController.test.ts
index 8712deadaa..d444eccdab 100644
--- a/packages/network-enablement-controller/src/NetworkEnablementController.test.ts
+++ b/packages/network-enablement-controller/src/NetworkEnablementController.test.ts
@@ -195,6 +195,7 @@ describe('NetworkEnablementController', () => {
           [ChainId[BuiltInNetworkName.OptimismMainnet]]: true,
           [ChainId[BuiltInNetworkName.PolygonMainnet]]: true,
           [ChainId[BuiltInNetworkName.SeiMainnet]]: true,
+          [ChainId[BuiltInNetworkName.MonadMainnet]]: true,
         },
         [KnownCaipNamespace.Solana]: {
           [SolScope.Mainnet]: true,
@@ -250,6 +251,7 @@ describe('NetworkEnablementController', () => {
           [ChainId[BuiltInNetworkName.OptimismMainnet]]: true,
           [ChainId[BuiltInNetworkName.PolygonMainnet]]: true,
           [ChainId[BuiltInNetworkName.SeiMainnet]]: true,
+          [ChainId[BuiltInNetworkName.MonadMainnet]]: true,
           '0xa86a': true, // Avalanche network added and enabled (keeps current selection)
         },
         [KnownCaipNamespace.Solana]: {
@@ -314,6 +316,7 @@ describe('NetworkEnablementController', () => {
           [ChainId[BuiltInNetworkName.OptimismMainnet]]: true,
           [ChainId[BuiltInNetworkName.PolygonMainnet]]: true,
           [ChainId[BuiltInNetworkName.SeiMainnet]]: true,
+          [ChainId[BuiltInNetworkName.MonadMainnet]]: true,
         },
         [KnownCaipNamespace.Solana]: {
           [SolScope.Mainnet]: true,
@@ -418,6 +421,7 @@ describe('NetworkEnablementController', () => {
     controller.disableNetwork('0xa'); // Optimism Mainnet
     controller.disableNetwork('0x89'); // Polygon Mainnet
     controller.disableNetwork('0x531'); // Sei Mainnet
+    controller.disableNetwork('0x8f'); // Monad Mainnet
 
     // Publish an update with linea network removed
     rootMessenger.publish('NetworkController:networkRemoved', {
@@ -455,6 +459,7 @@ describe('NetworkEnablementController', () => {
           [ChainId[BuiltInNetworkName.OptimismMainnet]]: false,
           [ChainId[BuiltInNetworkName.PolygonMainnet]]: false,
           [ChainId[BuiltInNetworkName.SeiMainnet]]: false,
+          [ChainId[BuiltInNetworkName.MonadMainnet]]: false,
         },
         [KnownCaipNamespace.Solana]: {
           [SolScope.Mainnet]: true,
@@ -555,6 +560,7 @@ describe('NetworkEnablementController', () => {
             [ChainId[BuiltInNetworkName.OptimismMainnet]]: true,
             [ChainId[BuiltInNetworkName.PolygonMainnet]]: true,
             [ChainId[BuiltInNetworkName.SeiMainnet]]: true,
+            [ChainId[BuiltInNetworkName.MonadMainnet]]: true,
           },
           [KnownCaipNamespace.Solana]: {
             [SolScope.Mainnet]: true, // Solana Mainnet (exists in multichain config)
@@ -1197,6 +1203,7 @@ describe('NetworkEnablementController', () => {
             [ChainId[BuiltInNetworkName.OptimismMainnet]]: true,
             [ChainId[BuiltInNetworkName.PolygonMainnet]]: true,
             [ChainId[BuiltInNetworkName.SeiMainnet]]: true,
+            [ChainId[BuiltInNetworkName.MonadMainnet]]: true,
           },
           [KnownCaipNamespace.Solana]: {
             [SolScope.Mainnet]: true,
@@ -1231,6 +1238,7 @@ describe('NetworkEnablementController', () => {
             [ChainId[BuiltInNetworkName.OptimismMainnet]]: false, // Not in mocked config
             [ChainId[BuiltInNetworkName.PolygonMainnet]]: false, // Not in mocked config
             [ChainId[BuiltInNetworkName.SeiMainnet]]: false, // Not in mocked config
+            [ChainId[BuiltInNetworkName.MonadMainnet]]: false, // Not in mocked config
           },
           [KnownCaipNamespace.Solana]: {
             [SolScope.Mainnet]: true, // Solana
@@ -1494,6 +1502,7 @@ describe('NetworkEnablementController', () => {
             [ChainId[BuiltInNetworkName.OptimismMainnet]]: true,
             [ChainId[BuiltInNetworkName.PolygonMainnet]]: true,
             [ChainId[BuiltInNetworkName.SeiMainnet]]: true,
+            [ChainId[BuiltInNetworkName.MonadMainnet]]: true,
           },
           [KnownCaipNamespace.Solana]: {
             [SolScope.Mainnet]: true,
@@ -1528,6 +1537,7 @@ describe('NetworkEnablementController', () => {
             [ChainId[BuiltInNetworkName.OptimismMainnet]]: false,
             [ChainId[BuiltInNetworkName.PolygonMainnet]]: false,
             [ChainId[BuiltInNetworkName.SeiMainnet]]: false,
+            [ChainId[BuiltInNetworkName.MonadMainnet]]: false,
           },
           [KnownCaipNamespace.Solana]: {
             [SolScope.Mainnet]: false, // Now disabled (cross-namespace behavior)
@@ -1582,6 +1592,7 @@ describe('NetworkEnablementController', () => {
             [ChainId[BuiltInNetworkName.OptimismMainnet]]: false,
             [ChainId[BuiltInNetworkName.PolygonMainnet]]: false,
             [ChainId[BuiltInNetworkName.SeiMainnet]]: false,
+            [ChainId[BuiltInNetworkName.MonadMainnet]]: false,
           },
           [KnownCaipNamespace.Solana]: {
             [SolScope.Mainnet]: false, // Disabled due to cross-namespace behavior
@@ -1620,6 +1631,7 @@ describe('NetworkEnablementController', () => {
             [ChainId[BuiltInNetworkName.OptimismMainnet]]: false,
             [ChainId[BuiltInNetworkName.PolygonMainnet]]: false,
             [ChainId[BuiltInNetworkName.SeiMainnet]]: false,
+            [ChainId[BuiltInNetworkName.MonadMainnet]]: false,
           },
           [KnownCaipNamespace.Solana]: {
             [SolScope.Mainnet]: false, // Now disabled (cross-namespace behavior)
@@ -1658,6 +1670,7 @@ describe('NetworkEnablementController', () => {
             [ChainId[BuiltInNetworkName.OptimismMainnet]]: false,
             [ChainId[BuiltInNetworkName.PolygonMainnet]]: false,
             [ChainId[BuiltInNetworkName.SeiMainnet]]: false,
+            [ChainId[BuiltInNetworkName.MonadMainnet]]: false,
           },
           [KnownCaipNamespace.Solana]: {
             [SolScope.Mainnet]: false, // Now disabled (cross-namespace behavior)
@@ -1707,6 +1720,7 @@ describe('NetworkEnablementController', () => {
             [ChainId[BuiltInNetworkName.OptimismMainnet]]: false,
             [ChainId[BuiltInNetworkName.PolygonMainnet]]: false,
             [ChainId[BuiltInNetworkName.SeiMainnet]]: false,
+            [ChainId[BuiltInNetworkName.MonadMainnet]]: false,
           },
           [KnownCaipNamespace.Solana]: {
             [SolScope.Mainnet]: false, // Disabled due to cross-namespace behavior
@@ -1753,6 +1767,7 @@ describe('NetworkEnablementController', () => {
             [ChainId[BuiltInNetworkName.OptimismMainnet]]: false,
             [ChainId[BuiltInNetworkName.PolygonMainnet]]: false,
             [ChainId[BuiltInNetworkName.SeiMainnet]]: false,
+            [ChainId[BuiltInNetworkName.MonadMainnet]]: false,
           },
           [KnownCaipNamespace.Solana]: {
             [SolScope.Mainnet]: false,
@@ -1802,6 +1817,7 @@ describe('NetworkEnablementController', () => {
             [ChainId[BuiltInNetworkName.OptimismMainnet]]: false,
             [ChainId[BuiltInNetworkName.PolygonMainnet]]: false,
             [ChainId[BuiltInNetworkName.SeiMainnet]]: false,
+            [ChainId[BuiltInNetworkName.MonadMainnet]]: false,
           },
           [KnownCaipNamespace.Solana]: {
             [SolScope.Mainnet]: false, // Disabled due to cross-namespace behavior
@@ -1848,6 +1864,7 @@ describe('NetworkEnablementController', () => {
             [ChainId[BuiltInNetworkName.OptimismMainnet]]: true,
             [ChainId[BuiltInNetworkName.PolygonMainnet]]: true,
             [ChainId[BuiltInNetworkName.SeiMainnet]]: true,
+            [ChainId[BuiltInNetworkName.MonadMainnet]]: true,
           },
           [KnownCaipNamespace.Solana]: {
             [SolScope.Mainnet]: true,
@@ -1896,6 +1913,7 @@ describe('NetworkEnablementController', () => {
             [ChainId[BuiltInNetworkName.OptimismMainnet]]: true,
             [ChainId[BuiltInNetworkName.PolygonMainnet]]: true,
             [ChainId[BuiltInNetworkName.SeiMainnet]]: true,
+            [ChainId[BuiltInNetworkName.MonadMainnet]]: true,
           },
           [KnownCaipNamespace.Solana]: {
             [SolScope.Mainnet]: true,
diff --git a/packages/network-enablement-controller/src/NetworkEnablementController.ts b/packages/network-enablement-controller/src/NetworkEnablementController.ts
index 8ea80bcc98..ffc5a77578 100644
--- a/packages/network-enablement-controller/src/NetworkEnablementController.ts
+++ b/packages/network-enablement-controller/src/NetworkEnablementController.ts
@@ -167,6 +167,7 @@ const getDefaultNetworkEnablementControllerState =
         [ChainId[BuiltInNetworkName.OptimismMainnet]]: true,
         [ChainId[BuiltInNetworkName.PolygonMainnet]]: true,
         [ChainId[BuiltInNetworkName.SeiMainnet]]: true,
+        [ChainId[BuiltInNetworkName.MonadMainnet]]: true,
       },
       [KnownCaipNamespace.Solana]: {
         [SolScope.Mainnet]: true,