diff --git a/src/api/providers/__tests__/bedrock.spec.ts b/src/api/providers/__tests__/bedrock.spec.ts
index 0ea487eb44..975e38af12 100644
--- a/src/api/providers/__tests__/bedrock.spec.ts
+++ b/src/api/providers/__tests__/bedrock.spec.ts
@@ -1275,4 +1275,56 @@ describe("AwsBedrockHandler", () => {
 			expect(mockCaptureException).toHaveBeenCalled()
 		})
 	})
+
+	describe("prompt cache default behavior", () => {
+		beforeEach(() => {
+			mockConverseStreamCommand.mockReset()
+		})
+
+		// System prompt must exceed minTokensPerCachePoint (1024) for cache points to be placed
+		const longSystemPrompt = "You are a helpful assistant. ".repeat(200)
+		const messages: Anthropic.Messages.MessageParam[] = [{ role: "user", content: "Hello" }]
+
+		it("should enable prompt caching by default when awsUsePromptCache is undefined", async () => {
+			const defaultHandler = new AwsBedrockHandler({
+				apiModelId: "anthropic.claude-3-5-sonnet-20241022-v2:0",
+				awsAccessKey: "test-access-key",
+				awsSecretKey: "test-secret-key",
+				awsRegion: "us-east-1",
+				// awsUsePromptCache is intentionally omitted (undefined)
+			})
+
+			const generator = defaultHandler.createMessage(longSystemPrompt, messages)
+			await generator.next() // Start the generator
+
+			expect(mockConverseStreamCommand).toHaveBeenCalled()
+			const commandArg = mockConverseStreamCommand.mock.calls[0][0] as any
+
+			// System content should include a cachePoint entry since prompt caching defaults to ON
+			const systemBlocks = commandArg.system
+			const hasCachePoint = systemBlocks?.some((block: any) => block.cachePoint !== undefined)
+			expect(hasCachePoint).toBe(true)
+		})
+
+		it("should disable prompt caching when awsUsePromptCache is explicitly false", async () => {
+			const disabledHandler = new AwsBedrockHandler({
+				apiModelId: "anthropic.claude-3-5-sonnet-20241022-v2:0",
+				awsAccessKey: "test-access-key",
+				awsSecretKey: "test-secret-key",
+				awsRegion: "us-east-1",
+				awsUsePromptCache: false,
+			})
+
+			const generator = disabledHandler.createMessage(longSystemPrompt, messages)
+			await generator.next() // Start the generator
+
+			expect(mockConverseStreamCommand).toHaveBeenCalled()
+			const commandArg = mockConverseStreamCommand.mock.calls[0][0] as any
+
+			// System content should NOT include cachePoint since caching is explicitly disabled
+			const systemBlocks = commandArg.system
+			const hasCachePoint = systemBlocks?.some((block: any) => block.cachePoint !== undefined)
+			expect(hasCachePoint).toBe(false)
+		})
+	})
 })
diff --git a/src/api/providers/bedrock.ts b/src/api/providers/bedrock.ts
index 6bcf57d42a..3ceb251003 100644
--- a/src/api/providers/bedrock.ts
+++ b/src/api/providers/bedrock.ts
@@ -357,7 +357,9 @@ export class AwsBedrockHandler extends BaseProvider implements SingleCompletionH
 		},
 	): ApiStream {
 		const modelConfig = this.getModel()
-		const usePromptCache = Boolean(this.options.awsUsePromptCache && this.supportsAwsPromptCache(modelConfig))
+		const usePromptCache = Boolean(
+			(this.options.awsUsePromptCache ?? true) && this.supportsAwsPromptCache(modelConfig),
+		)
 
 		const conversationId =
 			messages.length > 0
diff --git a/webview-ui/src/components/settings/providers/Bedrock.tsx b/webview-ui/src/components/settings/providers/Bedrock.tsx
index d9c69f8a8e..ed554f126d 100644
--- a/webview-ui/src/components/settings/providers/Bedrock.tsx
+++ b/webview-ui/src/components/settings/providers/Bedrock.tsx
@@ -198,7 +198,7 @@ export const Bedrock = ({ apiConfiguration, setApiConfigurationField, selectedMo
 			{selectedModelInfo?.supportsPromptCache && (
 				<>
 					<Checkbox
-						checked={apiConfiguration?.awsUsePromptCache || false}
+						checked={apiConfiguration?.awsUsePromptCache ?? true}
 						onChange={handleInputChange("awsUsePromptCache", noTransform)}>
 						<div className="flex items-center gap-1">
 							<span>{t("settings:providers.enablePromptCaching")}</span>
diff --git a/webview-ui/src/components/ui/hooks/__tests__/useSelectedModel.spec.ts b/webview-ui/src/components/ui/hooks/__tests__/useSelectedModel.spec.ts
index a8dead311f..2c24e4b565 100644
--- a/webview-ui/src/components/ui/hooks/__tests__/useSelectedModel.spec.ts
+++ b/webview-ui/src/components/ui/hooks/__tests__/useSelectedModel.spec.ts
@@ -496,6 +496,52 @@ describe("useSelectedModel", () => {
 		})
 	})
 
+	describe("bedrock provider with custom ARN", () => {
+		beforeEach(() => {
+			mockUseRouterModels.mockReturnValue({
+				data: {
+					openrouter: {},
+					requesty: {},
+					litellm: {},
+				},
+				isLoading: false,
+				isError: false,
+			} as any)
+
+			mockUseOpenRouterModelProviders.mockReturnValue({
+				data: {},
+				isLoading: false,
+				isError: false,
+			} as any)
+		})
+
+		it("should enable supportsPromptCache for custom-arn model", () => {
+			const apiConfiguration: ProviderSettings = {
+				apiProvider: "bedrock",
+				apiModelId: "custom-arn",
+			}
+
+			const wrapper = createWrapper()
+			const { result } = renderHook(() => useSelectedModel(apiConfiguration), { wrapper })
+
+			expect(result.current.id).toBe("custom-arn")
+			expect(result.current.info?.supportsPromptCache).toBe(true)
+		})
+
+		it("should enable supportsImages for custom-arn model", () => {
+			const apiConfiguration: ProviderSettings = {
+				apiProvider: "bedrock",
+				apiModelId: "custom-arn",
+			}
+
+			const wrapper = createWrapper()
+			const { result } = renderHook(() => useSelectedModel(apiConfiguration), { wrapper })
+
+			expect(result.current.id).toBe("custom-arn")
+			expect(result.current.info?.supportsImages).toBe(true)
+		})
+	})
+
 	describe("litellm provider", () => {
 		beforeEach(() => {
 			mockUseOpenRouterModelProviders.mockReturnValue({
diff --git a/webview-ui/src/components/ui/hooks/useSelectedModel.ts b/webview-ui/src/components/ui/hooks/useSelectedModel.ts
index 8a6e49e212..959deff2b7 100644
--- a/webview-ui/src/components/ui/hooks/useSelectedModel.ts
+++ b/webview-ui/src/components/ui/hooks/useSelectedModel.ts
@@ -182,7 +182,7 @@ function getSelectedModel({
 			if (id === "custom-arn") {
 				return {
 					id,
-					info: { maxTokens: 5000, contextWindow: 128_000, supportsPromptCache: false, supportsImages: true },
+					info: { maxTokens: 5000, contextWindow: 128_000, supportsPromptCache: true, supportsImages: true },
 				}
 			}