diff --git a/.server-changes/native-build-server-opt-out.md b/.server-changes/native-build-server-opt-out.md
new file mode 100644
index 00000000000..2e43b143480
--- /dev/null
+++ b/.server-changes/native-build-server-opt-out.md
@@ -0,0 +1,6 @@
+---
+area: webapp
+type: improvement
+---
+
+Make the native build server the default in project build settings. It's now opt-out, stored as a new `disableNativeBuildServer` key. Also clarifies in the UI that build settings apply to GitHub-triggered and native build server deployments.
diff --git a/apps/webapp/app/routes/_app.orgs.$organizationSlug.projects.$projectParam.env.$envParam.settings.integrations/route.tsx b/apps/webapp/app/routes/_app.orgs.$organizationSlug.projects.$projectParam.env.$envParam.settings.integrations/route.tsx
index 2178d19f99b..644dcc18f87 100644
--- a/apps/webapp/app/routes/_app.orgs.$organizationSlug.projects.$projectParam.env.$envParam.settings.integrations/route.tsx
+++ b/apps/webapp/app/routes/_app.orgs.$organizationSlug.projects.$projectParam.env.$envParam.settings.integrations/route.tsx
@@ -112,6 +112,8 @@ const UpdateBuildSettingsFormSchema = z.object({
     .refine((val) => !val || val.length <= 500, {
       message: "Pre-build command must not exceed 500 characters",
     }),
+  // Positive checkbox in the UI ("Use native build server"). It is checked by
+  // default; we store the inverse as `disableNativeBuildServer`.
   useNativeBuildServer: z
     .string()
     .optional()
@@ -152,7 +154,8 @@ export const action: ActionFunction = async ({ request, params }) => {
     installCommand: installCommand || undefined,
     preBuildCommand: preBuildCommand || undefined,
     triggerConfigFilePath: triggerConfigFilePath || undefined,
-    useNativeBuildServer: useNativeBuildServer,
+    // Native build server is the default, so we only persist the opt-out.
+    disableNativeBuildServer: useNativeBuildServer ? undefined : true,
   });
 
   if (resultOrFail.isErr()) {
@@ -321,6 +324,10 @@ export default function IntegrationsSettingsPage() {
 
               <div>
                 <Header2 spacing>Build settings</Header2>
+                <Hint className="mb-2">
+                  These settings apply to GitHub-triggered deployments and deployments built with
+                  the native build server.
+                </Hint>
                 <div className="w-full rounded-sm border border-grid-dimmed p-4">
                   <BuildSettingsForm buildSettings={buildSettings ?? {}} />
                 </div>
@@ -362,11 +369,14 @@ function BuildSettingsForm({ buildSettings }: { buildSettings: BuildSettings })
   const navigation = useNavigation();
 
   const [hasBuildSettingsChanges, setHasBuildSettingsChanges] = useState(false);
+  // The native build server is enabled by default; it's only off when the
+  // project has explicitly opted out via `disableNativeBuildServer`.
+  const nativeBuildServerEnabled = buildSettings?.disableNativeBuildServer !== true;
   const [buildSettingsValues, setBuildSettingsValues] = useState({
     preBuildCommand: buildSettings?.preBuildCommand || "",
     installCommand: buildSettings?.installCommand || "",
     triggerConfigFilePath: buildSettings?.triggerConfigFilePath || "",
-    useNativeBuildServer: buildSettings?.useNativeBuildServer || false,
+    useNativeBuildServer: nativeBuildServerEnabled,
   });
 
   useEffect(() => {
@@ -374,9 +384,9 @@ function BuildSettingsForm({ buildSettings }: { buildSettings: BuildSettings })
       buildSettingsValues.preBuildCommand !== (buildSettings?.preBuildCommand || "") ||
       buildSettingsValues.installCommand !== (buildSettings?.installCommand || "") ||
       buildSettingsValues.triggerConfigFilePath !== (buildSettings?.triggerConfigFilePath || "") ||
-      buildSettingsValues.useNativeBuildServer !== (buildSettings?.useNativeBuildServer || false);
+      buildSettingsValues.useNativeBuildServer !== nativeBuildServerEnabled;
     setHasBuildSettingsChanges(hasChanges);
-  }, [buildSettingsValues, buildSettings]);
+  }, [buildSettingsValues, buildSettings, nativeBuildServerEnabled]);
 
   const [buildSettingsForm, fields] = useForm({
     id: "update-build-settings",
@@ -462,7 +472,7 @@ function BuildSettingsForm({ buildSettings }: { buildSettings: BuildSettings })
               {...conform.input(fields.useNativeBuildServer, { type: "checkbox" })}
               label="Use native build server"
               variant="simple/small"
-              defaultChecked={buildSettings?.useNativeBuildServer || false}
+              defaultChecked={nativeBuildServerEnabled}
               onChange={(isChecked) => {
                 setBuildSettingsValues((prev) => ({
                   ...prev,
@@ -471,8 +481,8 @@ function BuildSettingsForm({ buildSettings }: { buildSettings: BuildSettings })
               }}
             />
             <Hint>
-              Native build server builds do not rely on external build providers and will become the
-              default in the future. Version 4.2.0 or newer is required.
+              Native build server builds don't rely on external build providers and are used by
+              default. Requires version 4.2.0 or newer.
             </Hint>
             <FormError id={fields.useNativeBuildServer.errorId}>
               {fields.useNativeBuildServer.error}
diff --git a/apps/webapp/app/v3/buildSettings.ts b/apps/webapp/app/v3/buildSettings.ts
index 1ff88caa9d1..0735de9f337 100644
--- a/apps/webapp/app/v3/buildSettings.ts
+++ b/apps/webapp/app/v3/buildSettings.ts
@@ -4,7 +4,9 @@ export const BuildSettingsSchema = z.object({
   triggerConfigFilePath: z.string().optional(),
   installCommand: z.string().optional(),
   preBuildCommand: z.string().optional(),
-  useNativeBuildServer: z.boolean().optional(),
+  // Opt-out flag: the native build server is used by default. Only set when a
+  // project explicitly disables it. Absence means native build server enabled.
+  disableNativeBuildServer: z.boolean().optional(),
 });
 
 export type BuildSettings = z.infer<typeof BuildSettingsSchema>;