diff --git a/.changeset/great-schools-cheer.md b/.changeset/great-schools-cheer.md
new file mode 100644
index 00000000000..a845151cc84
--- /dev/null
+++ b/.changeset/great-schools-cheer.md
@@ -0,0 +1,2 @@
+---
+---
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/RuntimeConfigGenerator.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/RuntimeConfigGenerator.java
index c40851880a4..2433e7f5168 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/RuntimeConfigGenerator.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/RuntimeConfigGenerator.java
@@ -169,11 +169,17 @@ void generate(LanguageTarget target) {
                     .replaceFirst(CodegenUtils.SOURCE_FOLDER + "/", ""))
                 .replace("${clientConfigName}", symbolProvider.toSymbol(service).getName() + "Config")
                 .replace("${apiVersion}", service.getVersion())
-                .replace("$", "$$") // sanitize template place holders.
-                .replace("$${customizations}", "${L@customizations}");
+                .replace("${", "$${") // sanitize template place holders.
+                .replace("$${customizations}", "${L@customizations}")
+                .replace("$${prepareCustomizations}", "${L@prepareCustomizations}");
 
         delegator.useFileWriter(target.getTargetFilename(), writer -> {
             // Inject customizations into the ~template.
+            writer.onSection("prepareCustomizations", original -> {
+                for (TypeScriptIntegration integration : integrations) {
+                    integration.prepareCustomizations(writer, target, settings, model);
+                }
+            });
             writer.indent().onSection("customizations", original -> {
                 // Start with defaults, use a TreeMap for keeping entries sorted.
                 Map<String, Consumer<TypeScriptWriter>> configs =
@@ -198,7 +204,7 @@ void generate(LanguageTarget target) {
                 });
             });
             writer.dedent();
-            writer.write(contents, "");
+            writer.write(contents, "", "");
         });
     }
 
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/TypeScriptIntegration.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/TypeScriptIntegration.java
index bc612cedda4..5c2f11379ce 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/TypeScriptIntegration.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/TypeScriptIntegration.java
@@ -253,4 +253,17 @@ default Map<String, Consumer<TypeScriptWriter>> getRuntimeConfigWriters(
     default List<ExtensionConfigurationInterface> getExtensionConfigurationInterfaces() {
         return Collections.emptyList();
     }
+
+    /**
+     * Allows the customization to write arbitrary preparatory code prior to the returned config object.
+     */
+    @SmithyInternalApi
+    default void prepareCustomizations(
+        TypeScriptWriter writer,
+        LanguageTarget target,
+        TypeScriptSettings settings,
+        Model model
+    ) {
+        return;
+    }
 }
diff --git a/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.browser.ts.template b/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.browser.ts.template
index a6a8eb1e9ee..1d42f61d15c 100644
--- a/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.browser.ts.template
+++ b/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.browser.ts.template
@@ -10,7 +10,7 @@ export const getRuntimeConfig = (config: ${clientConfigName}) => {
   const defaultsMode = resolveDefaultsModeConfig(config);
   const defaultConfigProvider = () => defaultsMode().then(loadConfigsForDefaultMode);
   const clientSharedValues = getSharedRuntimeConfig(config);
-  return {
+  ${prepareCustomizations}return {
     ...clientSharedValues,
     ...config,
     runtime: "browser",
diff --git a/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.native.ts.template b/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.native.ts.template
index 705735d7203..9d24bec16a6 100644
--- a/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.native.ts.template
+++ b/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.native.ts.template
@@ -6,7 +6,7 @@ import { getRuntimeConfig as getBrowserRuntimeConfig } from "./runtimeConfig.bro
  */
 export const getRuntimeConfig = (config: ${clientConfigName}) => {
   const browserDefaults = getBrowserRuntimeConfig(config);
-  return {
+  ${prepareCustomizations}return {
     ...browserDefaults,
     ...config,
     runtime: "react-native",
diff --git a/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.shared.ts.template b/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.shared.ts.template
index 5ec08befe15..b83ca69f052 100644
--- a/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.shared.ts.template
+++ b/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.shared.ts.template
@@ -3,7 +3,9 @@ import { ${clientConfigName} } from "${clientModuleName}";
 /**
  * @internal
  */
-export const getRuntimeConfig = (config: ${clientConfigName}) => ({
-  apiVersion: "${apiVersion}",
-${customizations}
-});
+export const getRuntimeConfig = (config: ${clientConfigName}) => {
+  ${prepareCustomizations}return {
+    apiVersion: "${apiVersion}",
+    ${customizations}
+  }
+};
diff --git a/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.ts.template b/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.ts.template
index e55472de15b..5f9234674e5 100644
--- a/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.ts.template
+++ b/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.ts.template
@@ -12,7 +12,7 @@ export const getRuntimeConfig = (config: ${clientConfigName}) => {
   const defaultsMode = resolveDefaultsModeConfig(config);
   const defaultConfigProvider = () => defaultsMode().then(loadConfigsForDefaultMode);
   const clientSharedValues = getSharedRuntimeConfig(config);
-  return {
+  ${prepareCustomizations}return {
     ...clientSharedValues,
     ...config,
     runtime: "node",