diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1f1e6fc391..573d1cf367 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,8 @@ This is the log of notable changes to EAS CLI and related packages.
 
 ### 🛠 Breaking changes
 
+- Require --environment flag for update commands when SDK >= 55. ([#3398](https://github.com/expo/eas-cli/pull/3398) by [@douglowder](https://github.com/douglowder))
+
 ### 🎉 New features
 
 ### 🐛 Bug fixes
diff --git a/packages/eas-cli/src/commandUtils/flags.ts b/packages/eas-cli/src/commandUtils/flags.ts
index bc108e1550..4e39763d86 100644
--- a/packages/eas-cli/src/commandUtils/flags.ts
+++ b/packages/eas-cli/src/commandUtils/flags.ts
@@ -67,7 +67,7 @@ export const EasJsonOnlyFlag = {
 export const EasUpdateEnvironmentFlag = {
   environment: Flags.string({
     description:
-      'Environment to use for the server-side defined EAS environment variables during command execution, e.g. "production", "preview", "development"',
+      'Environment to use for the server-side defined EAS environment variables during command execution, e.g. "production", "preview", "development". Required for projects using Expo SDK 55 or greater.',
     required: false,
     default: undefined,
   }),
diff --git a/packages/eas-cli/src/commands/update/__tests__/index.test.ts b/packages/eas-cli/src/commands/update/__tests__/index.test.ts
index dd03a19b82..b0acbc394a 100644
--- a/packages/eas-cli/src/commands/update/__tests__/index.test.ts
+++ b/packages/eas-cli/src/commands/update/__tests__/index.test.ts
@@ -143,6 +143,67 @@ describe(UpdatePublish.name, () => {
     expect(PublishMutation.publishUpdateGroupAsync).toHaveBeenCalled();
   });
 
+  it('errors when SDK >= 55 and --environment is not provided', async () => {
+    const flags = ['--non-interactive', '--branch=branch123', '--message=abc'];
+
+    mockTestProject({ expoConfig: { sdkVersion: '55.0.0' } });
+
+    await expect(new UpdatePublish(flags, commandOptions).run()).rejects.toThrow(
+      '--environment flag is required for projects using Expo SDK 55 or greater'
+    );
+  });
+
+  it('does not error when SDK >= 55 and --environment is provided', async () => {
+    const flags = [
+      '--non-interactive',
+      '--branch=branch123',
+      '--message=abc',
+      '--environment=production',
+    ];
+
+    mockTestProject({ expoConfig: { sdkVersion: '55.0.0' } });
+    const { platforms, runtimeVersion } = mockTestExport();
+
+    jest.mocked(ensureBranchExistsAsync).mockResolvedValue({
+      branch: {
+        id: 'branch123',
+        name: 'wat',
+      },
+      createdBranch: false,
+    });
+
+    jest
+      .mocked(PublishMutation.publishUpdateGroupAsync)
+      .mockResolvedValue(platforms.map(platform => ({ ...updateStub, platform, runtimeVersion })));
+
+    await new UpdatePublish(flags, commandOptions).run();
+
+    expect(PublishMutation.publishUpdateGroupAsync).toHaveBeenCalled();
+  });
+
+  it('does not error when SDK < 55 and --environment is not provided', async () => {
+    const flags = ['--non-interactive', '--branch=branch123', '--message=abc'];
+
+    mockTestProject({ expoConfig: { sdkVersion: '54.0.0' } });
+    const { platforms, runtimeVersion } = mockTestExport();
+
+    jest.mocked(ensureBranchExistsAsync).mockResolvedValue({
+      branch: {
+        id: 'branch123',
+        name: 'wat',
+      },
+      createdBranch: false,
+    });
+
+    jest
+      .mocked(PublishMutation.publishUpdateGroupAsync)
+      .mockResolvedValue(platforms.map(platform => ({ ...updateStub, platform, runtimeVersion })));
+
+    await new UpdatePublish(flags, commandOptions).run();
+
+    expect(PublishMutation.publishUpdateGroupAsync).toHaveBeenCalled();
+  });
+
   it('creates a new update with the public expo config', async () => {
     const flags = ['--non-interactive', '--branch=branch123', '--message=abc'];
 
diff --git a/packages/eas-cli/src/commands/update/configure.ts b/packages/eas-cli/src/commands/update/configure.ts
index 8b86d4f036..3a617c892b 100644
--- a/packages/eas-cli/src/commands/update/configure.ts
+++ b/packages/eas-cli/src/commands/update/configure.ts
@@ -11,6 +11,7 @@ import {
   ensureEASUpdateIsConfiguredAsync,
   ensureEASUpdateIsConfiguredInEasJsonAsync,
 } from '../../update/configure';
+import { assertEnvironmentFlagForSdk55OrGreater } from '../../update/utils';
 
 export default class UpdateConfigure extends EasCommand {
   static override description = 'configure the project to support EAS Update';
@@ -42,6 +43,11 @@ export default class UpdateConfigure extends EasCommand {
       withServerSideEnvironment: flags['environment'] ?? null,
     });
 
+    assertEnvironmentFlagForSdk55OrGreater({
+      sdkVersion: exp.sdkVersion,
+      environment: flags['environment'],
+    });
+
     Log.log(
       '💡 The following process will configure your project to use EAS Update. These changes only apply to your local project files and you can safely revert them at any time.'
     );
diff --git a/packages/eas-cli/src/commands/update/index.ts b/packages/eas-cli/src/commands/update/index.ts
index a3deda1632..e61da9b9b7 100644
--- a/packages/eas-cli/src/commands/update/index.ts
+++ b/packages/eas-cli/src/commands/update/index.ts
@@ -9,6 +9,7 @@ import { ensureRepoIsCleanAsync } from '../../build/utils/repository';
 import { getUpdateGroupUrl } from '../../build/utils/url';
 import EasCommand from '../../commandUtils/EasCommand';
 import { EasNonInteractiveAndJsonFlags, EasUpdateEnvironmentFlag } from '../../commandUtils/flags';
+import { assertEnvironmentFlagForSdk55OrGreater } from '../../update/utils';
 import { getPaginatedQueryOptions } from '../../commandUtils/pagination';
 import fetch from '../../fetch';
 import {
@@ -249,6 +250,11 @@ export default class UpdatePublish extends EasCommand {
       projectDir,
     } = await getDynamicPublicProjectConfigAsync();
 
+    assertEnvironmentFlagForSdk55OrGreater({
+      sdkVersion: expPossiblyWithoutEasUpdateConfigured.sdkVersion,
+      environment,
+    });
+
     await maybeWarnAboutEasOutagesAsync(graphqlClient, [StatuspageServiceName.EasUpdate]);
 
     const easJsonAccessor = EasJsonAccessor.fromProjectPath(projectDir);
diff --git a/packages/eas-cli/src/update/utils.ts b/packages/eas-cli/src/update/utils.ts
index 98f804aab0..cf66498eb8 100644
--- a/packages/eas-cli/src/update/utils.ts
+++ b/packages/eas-cli/src/update/utils.ts
@@ -1,7 +1,9 @@
 import { ExpoConfig } from '@expo/config';
+import { Errors } from '@oclif/core';
 import { format } from '@expo/timeago.js';
 import chalk from 'chalk';
 import dateFormat from 'dateformat';
+import semver from 'semver';
 
 import { ExpoGraphqlClient } from '../commandUtils/context/contextUtils/createGraphqlClient';
 import {
@@ -357,3 +359,20 @@ export const updatePublishPlatformToAppPlatform: Record<UpdatePublishPlatform, A
   android: AppPlatform.Android,
   ios: AppPlatform.Ios,
 };
+
+export function assertEnvironmentFlagForSdk55OrGreater({
+  sdkVersion,
+  environment,
+}: {
+  sdkVersion: string | undefined;
+  environment: string | undefined;
+}): void {
+  if (process.env.EAS_BUILD) {
+    return;
+  }
+  if (sdkVersion && semver.gte(sdkVersion, '55.0.0') && !environment) {
+    Errors.error('--environment flag is required for projects using Expo SDK 55 or greater', {
+      exit: 1,
+    });
+  }
+}