diff --git a/.changeset/stupid-papayas-kneel.md b/.changeset/stupid-papayas-kneel.md
new file mode 100644
index 0000000000..4cfeda6653
--- /dev/null
+++ b/.changeset/stupid-papayas-kneel.md
@@ -0,0 +1,7 @@
+---
+"@cloudflare/workers-utils": patch
+---
+
+Make all properties in `previews` optional
+
+All properties in `previews` were previously incorrectly typed as required.
diff --git a/packages/workers-utils/src/config/environment.ts b/packages/workers-utils/src/config/environment.ts
index 01a4361b5c..aaac98544a 100644
--- a/packages/workers-utils/src/config/environment.ts
+++ b/packages/workers-utils/src/config/environment.ts
@@ -1607,5 +1607,7 @@ export type ContainerEngine =
  */
 export interface PreviewsConfig
 	extends
-		EnvironmentNonInheritable,
-		Pick<EnvironmentInheritable, "logpush" | "observability" | "limits"> {}
+		Partial<EnvironmentNonInheritable>,
+		Partial<
+			Pick<EnvironmentInheritable, "logpush" | "observability" | "limits">
+		> {}
diff --git a/packages/wrangler/src/__tests__/preview.test.ts b/packages/wrangler/src/__tests__/preview.test.ts
index 51de704b58..1d7453c041 100644
--- a/packages/wrangler/src/__tests__/preview.test.ts
+++ b/packages/wrangler/src/__tests__/preview.test.ts
@@ -27,10 +27,10 @@ vi.mock("node:child_process", async () => {
 	};
 });
 
-function configWithPreviews(previews: Partial<PreviewsConfig>): Config {
+function configWithPreviews(previews: PreviewsConfig): Config {
 	return {
 		...defaultWranglerConfig,
-		previews: previews as PreviewsConfig,
+		previews,
 	};
 }