diff --git a/.changeset/extra-ca-certs-deploy.md b/.changeset/extra-ca-certs-deploy.md
new file mode 100644
index 00000000000..f86854b078a
--- /dev/null
+++ b/.changeset/extra-ca-certs-deploy.md
@@ -0,0 +1,5 @@
+---
+"trigger.dev": patch
+---
+
+Fix `extraCACerts` in `trigger.config.ts` having no effect on deployed tasks. The configured CA file is now copied into the deployment image via the `additionalFiles` build extension, and the deploy command passes its image path to the `NODE_EXTRA_CA_CERTS` build argument, so self-signed or corporate certificates are trusted at runtime.
diff --git a/packages/cli-v3/src/commands/deploy.ts b/packages/cli-v3/src/commands/deploy.ts
index 02f1a0bfcc4..987c042e564 100644
--- a/packages/cli-v3/src/commands/deploy.ts
+++ b/packages/cli-v3/src/commands/deploy.ts
@@ -50,7 +50,7 @@ import {
 } from "../cli/common.js";
 import { loadConfig } from "../config.js";
 import { authenticateForDeploy, userIdForDeploy } from "../deploy/auth.js";
-import { buildImage } from "../deploy/buildImage.js";
+import { buildImage, resolveExtraCACertsImagePath } from "../deploy/buildImage.js";
 import { type DeployEnvironment, resolveDeployEnvironment } from "../deploy/environment.js";
 import {
   checkLogsForErrors,
@@ -776,6 +776,10 @@ async function _deployCommand(dir: string, options: DeployCommandOptions) {
     externalBuildProjectId: deployment.externalBuildData?.projectId,
     projectId: projectClient.id,
     projectRef: resolvedConfig.project,
+    extraCACerts: resolveExtraCACertsImagePath(
+      resolvedConfig.extraCACerts,
+      resolvedConfig.workingDir
+    ),
     apiUrl: projectClient.client.apiURL,
     apiKey: projectClient.client.accessToken!,
     apiClient: projectClient.client,
diff --git a/packages/cli-v3/src/config.ts b/packages/cli-v3/src/config.ts
index a34138cd4c1..eb098e84043 100644
--- a/packages/cli-v3/src/config.ts
+++ b/packages/cli-v3/src/config.ts
@@ -301,6 +301,14 @@ async function autoDetectDirs(workingDir: string): Promise<string[]> {
 }
 
 function validateConfig(config: TriggerConfig, warn = true) {
+  if (config.extraCACerts) {
+    // The CA file must be inside the build output so the image can point
+    // NODE_EXTRA_CA_CERTS at it
+    config.build ??= {};
+    config.build.extensions ??= [];
+    config.build.extensions.push(additionalFiles({ files: [config.extraCACerts] }));
+  }
+
   if (config.additionalFiles && config.additionalFiles.length > 0) {
     warn &&
       prettyWarning(
diff --git a/packages/cli-v3/src/deploy/buildImage.test.ts b/packages/cli-v3/src/deploy/buildImage.test.ts
index a136c4c95a7..7c57a9e2b38 100644
--- a/packages/cli-v3/src/deploy/buildImage.test.ts
+++ b/packages/cli-v3/src/deploy/buildImage.test.ts
@@ -12,6 +12,7 @@ import {
   TOOLCHAIN_PACKAGES,
   formatCommandForDiagnostics,
   generateContainerfile,
+  resolveExtraCACertsImagePath,
 } from "./buildImage.js";
 import { EMSIGN_COMPROMISE_REJECTED_INTERMEDIATES } from "./emsignRejectedIntermediates.js";
 
@@ -56,6 +57,26 @@ const images: Array<[BuildRuntime, string, string]> = [
   ],
 ];
 
+describe("resolveExtraCACertsImagePath", () => {
+  it("returns undefined when no CA file is configured", () => {
+    expect(resolveExtraCACertsImagePath(undefined, "/project")).toBeUndefined();
+  });
+
+  it("maps a project-relative path into /app", () => {
+    expect(resolveExtraCACertsImagePath("./certs/ca.crt", "/project")).toBe("/app/certs/ca.crt");
+  });
+
+  it("strips leading parent segments the same way additionalFiles does", () => {
+    expect(resolveExtraCACertsImagePath("../shared/ca.crt", "/project")).toBe("/app/shared/ca.crt");
+  });
+
+  it("maps an absolute path inside the project into /app", () => {
+    expect(resolveExtraCACertsImagePath("/project/certs/ca.crt", "/project")).toBe(
+      "/app/certs/ca.crt"
+    );
+  });
+});
+
 describe("generateContainerfile", () => {
   it.each(images)("uses the pinned published base images for %s", async (runtime, base, build) => {
     const containerfile = await generateContainerfile({
diff --git a/packages/cli-v3/src/deploy/buildImage.ts b/packages/cli-v3/src/deploy/buildImage.ts
index c7f300b5060..061f535c91e 100644
--- a/packages/cli-v3/src/deploy/buildImage.ts
+++ b/packages/cli-v3/src/deploy/buildImage.ts
@@ -3,7 +3,7 @@ import { depot } from "@depot/cli";
 import { x } from "tinyexec";
 import type { BuildManifest, BuildRuntime } from "@trigger.dev/core/v3/schemas";
 import { networkInterfaces } from "os";
-import { join } from "path";
+import { isAbsolute, join, relative } from "path";
 import { safeReadJSONFile } from "../utilities/fileSystem.js";
 import { readFileSync } from "fs";
 
@@ -1305,3 +1305,25 @@ function getOutputOptions({
 
   return outputOptions;
 }
+
+// The extraCACerts config option is project-relative, but NODE_EXTRA_CA_CERTS
+// must point at the file inside the deployed image. additionalFiles copies it
+// into the build output root, which becomes /app in the image.
+export function resolveExtraCACertsImagePath(
+  extraCACerts: string | undefined,
+  workingDir: string
+): string | undefined {
+  if (!extraCACerts) {
+    return undefined;
+  }
+
+  const projectRelativePath = isAbsolute(extraCACerts)
+    ? relative(workingDir, extraCACerts)
+    : extraCACerts;
+
+  const segments = projectRelativePath
+    .split(/[\\/]+/)
+    .filter((segment) => segment && segment !== "." && segment !== "..");
+
+  return `/app/${segments.join("/")}`;
+}