diff --git a/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/badSignature/init.js b/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/badSignature/init.js
index dc92fbc296a4..1e0303b9c356 100644
--- a/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/badSignature/init.js
+++ b/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/badSignature/init.js
@@ -7,7 +7,7 @@ window.UnleashClient = class {
 };
 
 window.Sentry = Sentry;
-window.sentryUnleashIntegration = Sentry.unleashIntegration({ unleashClientClass: window.UnleashClient });
+window.sentryUnleashIntegration = Sentry.unleashIntegration({ featureFlagClientClass: window.UnleashClient });
 
 Sentry.init({
   dsn: 'https://public@dsn.ingest.sentry.io/1337',
diff --git a/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/badSignatureDeprecated/init.js b/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/badSignatureDeprecated/init.js
new file mode 100644
index 000000000000..dc92fbc296a4
--- /dev/null
+++ b/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/badSignatureDeprecated/init.js
@@ -0,0 +1,17 @@
+import * as Sentry from '@sentry/browser';
+
+window.UnleashClient = class {
+  isEnabled(x) {
+    return x;
+  }
+};
+
+window.Sentry = Sentry;
+window.sentryUnleashIntegration = Sentry.unleashIntegration({ unleashClientClass: window.UnleashClient });
+
+Sentry.init({
+  dsn: 'https://public@dsn.ingest.sentry.io/1337',
+  sampleRate: 1.0,
+  integrations: [window.sentryUnleashIntegration],
+  debug: true, // Required to test logging.
+});
diff --git a/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/badSignatureDeprecated/test.ts b/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/badSignatureDeprecated/test.ts
new file mode 100644
index 000000000000..9b95d4d51c81
--- /dev/null
+++ b/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/badSignatureDeprecated/test.ts
@@ -0,0 +1,59 @@
+import { expect } from '@playwright/test';
+
+import { sentryTest } from '../../../../../utils/fixtures';
+
+import { shouldSkipFeatureFlagsTest } from '../../../../../utils/helpers';
+
+sentryTest('Logs and returns if isEnabled does not match expected signature', async ({ getLocalTestUrl, page }) => {
+  if (shouldSkipFeatureFlagsTest()) {
+    sentryTest.skip();
+  }
+  const bundleKey = process.env.PW_BUNDLE || '';
+  const hasDebug = !bundleKey.includes('_min');
+
+  await page.route('https://dsn.ingest.sentry.io/**/*', route => {
+    return route.fulfill({
+      status: 200,
+      contentType: 'application/json',
+      body: JSON.stringify({ id: 'test-id' }),
+    });
+  });
+
+  const url = await getLocalTestUrl({ testDir: __dirname, skipDsnRouteHandler: true });
+  await page.goto(url);
+
+  const errorLogs: string[] = [];
+  page.on('console', msg => {
+    if (msg.type() == 'error') {
+      errorLogs.push(msg.text());
+    }
+  });
+
+  const results = await page.evaluate(() => {
+    const unleash = new (window as any).UnleashClient();
+    const res1 = unleash.isEnabled('my-feature');
+    const res2 = unleash.isEnabled(999);
+    const res3 = unleash.isEnabled({});
+    return [res1, res2, res3];
+  });
+
+  // Test that the expected results are still returned. Note isEnabled is identity function for this test.
+  expect(results).toEqual(['my-feature', 999, {}]);
+
+  // Expected error logs.
+  if (hasDebug) {
+    expect(errorLogs).toEqual(
+      expect.arrayContaining([
+        expect.stringContaining(
+          '[Feature Flags] UnleashClient.isEnabled does not match expected signature. arg0: my-feature (string), result: my-feature (string)',
+        ),
+        expect.stringContaining(
+          '[Feature Flags] UnleashClient.isEnabled does not match expected signature. arg0: 999 (number), result: 999 (number)',
+        ),
+        expect.stringContaining(
+          '[Feature Flags] UnleashClient.isEnabled does not match expected signature. arg0: [object Object] (object), result: [object Object] (object)',
+        ),
+      ]),
+    );
+  }
+});
diff --git a/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/basicDeprecated/init.js b/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/basicDeprecated/init.js
new file mode 100644
index 000000000000..9f1f28730cf7
--- /dev/null
+++ b/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/basicDeprecated/init.js
@@ -0,0 +1,50 @@
+import * as Sentry from '@sentry/browser';
+
+window.UnleashClient = class {
+  constructor() {
+    this._featureToVariant = {
+      strFeat: { name: 'variant1', enabled: true, feature_enabled: true, payload: { type: 'string', value: 'test' } },
+      noPayloadFeat: { name: 'eu-west', enabled: true, feature_enabled: true },
+      jsonFeat: {
+        name: 'paid-orgs',
+        enabled: true,
+        feature_enabled: true,
+        payload: {
+          type: 'json',
+          value: '{"foo": {"bar": "baz"}, "hello": [1, 2, 3]}',
+        },
+      },
+
+      // Enabled feature with no configured variants.
+      noVariantFeat: { name: 'disabled', enabled: false, feature_enabled: true },
+
+      // Disabled feature.
+      disabledFeat: { name: 'disabled', enabled: false, feature_enabled: false },
+    };
+
+    // Variant returned for features that don't exist.
+    // `feature_enabled` may be defined in prod, but we want to test the undefined case.
+    this._fallbackVariant = {
+      name: 'disabled',
+      enabled: false,
+    };
+  }
+
+  isEnabled(toggleName) {
+    const variant = this._featureToVariant[toggleName] || this._fallbackVariant;
+    return variant.feature_enabled || false;
+  }
+
+  getVariant(toggleName) {
+    return this._featureToVariant[toggleName] || this._fallbackVariant;
+  }
+};
+
+window.Sentry = Sentry;
+window.sentryUnleashIntegration = Sentry.unleashIntegration({ unleashClientClass: window.UnleashClient });
+
+Sentry.init({
+  dsn: 'https://public@dsn.ingest.sentry.io/1337',
+  sampleRate: 1.0,
+  integrations: [window.sentryUnleashIntegration],
+});
diff --git a/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/basicDeprecated/test.ts b/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/basicDeprecated/test.ts
new file mode 100644
index 000000000000..5bb72caddd24
--- /dev/null
+++ b/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/basicDeprecated/test.ts
@@ -0,0 +1,58 @@
+import { expect } from '@playwright/test';
+
+import { sentryTest } from '../../../../../utils/fixtures';
+
+import { envelopeRequestParser, shouldSkipFeatureFlagsTest, waitForErrorRequest } from '../../../../../utils/helpers';
+
+const FLAG_BUFFER_SIZE = 100; // Corresponds to constant in featureFlags.ts, in browser utils.
+
+sentryTest('Basic test with eviction, update, and no async tasks', async ({ getLocalTestUrl, page }) => {
+  if (shouldSkipFeatureFlagsTest()) {
+    sentryTest.skip();
+  }
+
+  await page.route('https://dsn.ingest.sentry.io/**/*', route => {
+    return route.fulfill({
+      status: 200,
+      contentType: 'application/json',
+      body: JSON.stringify({ id: 'test-id' }),
+    });
+  });
+
+  const url = await getLocalTestUrl({ testDir: __dirname, skipDsnRouteHandler: true });
+  await page.goto(url);
+
+  await page.evaluate(bufferSize => {
+    const client = new (window as any).UnleashClient();
+
+    client.isEnabled('feat1');
+    client.isEnabled('strFeat');
+    client.isEnabled('noPayloadFeat');
+    client.isEnabled('jsonFeat');
+    client.isEnabled('noVariantFeat');
+    client.isEnabled('disabledFeat');
+
+    for (let i = 7; i <= bufferSize; i++) {
+      client.isEnabled(`feat${i}`);
+    }
+    client.isEnabled(`feat${bufferSize + 1}`); // eviction
+    client.isEnabled('noPayloadFeat'); // update (move to tail)
+  }, FLAG_BUFFER_SIZE);
+
+  const reqPromise = waitForErrorRequest(page);
+  await page.locator('#error').click();
+  const req = await reqPromise;
+  const event = envelopeRequestParser(req);
+
+  const expectedFlags = [{ flag: 'strFeat', result: true }];
+  expectedFlags.push({ flag: 'jsonFeat', result: true });
+  expectedFlags.push({ flag: 'noVariantFeat', result: true });
+  expectedFlags.push({ flag: 'disabledFeat', result: false });
+  for (let i = 7; i <= FLAG_BUFFER_SIZE; i++) {
+    expectedFlags.push({ flag: `feat${i}`, result: false });
+  }
+  expectedFlags.push({ flag: `feat${FLAG_BUFFER_SIZE + 1}`, result: false });
+  expectedFlags.push({ flag: 'noPayloadFeat', result: true });
+
+  expect(event.contexts?.flags?.values).toEqual(expectedFlags);
+});
diff --git a/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/init.js b/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/init.js
index 9f1f28730cf7..ddc74b6427b4 100644
--- a/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/init.js
+++ b/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/init.js
@@ -41,7 +41,7 @@ window.UnleashClient = class {
 };
 
 window.Sentry = Sentry;
-window.sentryUnleashIntegration = Sentry.unleashIntegration({ unleashClientClass: window.UnleashClient });
+window.sentryUnleashIntegration = Sentry.unleashIntegration({ featureFlagClientClass: window.UnleashClient });
 
 Sentry.init({
   dsn: 'https://public@dsn.ingest.sentry.io/1337',
diff --git a/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/withScopeDeprecated/init.js b/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/withScopeDeprecated/init.js
new file mode 100644
index 000000000000..9f1f28730cf7
--- /dev/null
+++ b/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/withScopeDeprecated/init.js
@@ -0,0 +1,50 @@
+import * as Sentry from '@sentry/browser';
+
+window.UnleashClient = class {
+  constructor() {
+    this._featureToVariant = {
+      strFeat: { name: 'variant1', enabled: true, feature_enabled: true, payload: { type: 'string', value: 'test' } },
+      noPayloadFeat: { name: 'eu-west', enabled: true, feature_enabled: true },
+      jsonFeat: {
+        name: 'paid-orgs',
+        enabled: true,
+        feature_enabled: true,
+        payload: {
+          type: 'json',
+          value: '{"foo": {"bar": "baz"}, "hello": [1, 2, 3]}',
+        },
+      },
+
+      // Enabled feature with no configured variants.
+      noVariantFeat: { name: 'disabled', enabled: false, feature_enabled: true },
+
+      // Disabled feature.
+      disabledFeat: { name: 'disabled', enabled: false, feature_enabled: false },
+    };
+
+    // Variant returned for features that don't exist.
+    // `feature_enabled` may be defined in prod, but we want to test the undefined case.
+    this._fallbackVariant = {
+      name: 'disabled',
+      enabled: false,
+    };
+  }
+
+  isEnabled(toggleName) {
+    const variant = this._featureToVariant[toggleName] || this._fallbackVariant;
+    return variant.feature_enabled || false;
+  }
+
+  getVariant(toggleName) {
+    return this._featureToVariant[toggleName] || this._fallbackVariant;
+  }
+};
+
+window.Sentry = Sentry;
+window.sentryUnleashIntegration = Sentry.unleashIntegration({ unleashClientClass: window.UnleashClient });
+
+Sentry.init({
+  dsn: 'https://public@dsn.ingest.sentry.io/1337',
+  sampleRate: 1.0,
+  integrations: [window.sentryUnleashIntegration],
+});
diff --git a/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/withScopeDeprecated/test.ts b/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/withScopeDeprecated/test.ts
new file mode 100644
index 000000000000..2d821bf6c81d
--- /dev/null
+++ b/dev-packages/browser-integration-tests/suites/integrations/featureFlags/unleash/withScopeDeprecated/test.ts
@@ -0,0 +1,65 @@
+import { expect } from '@playwright/test';
+
+import { sentryTest } from '../../../../../utils/fixtures';
+
+import { envelopeRequestParser, shouldSkipFeatureFlagsTest, waitForErrorRequest } from '../../../../../utils/helpers';
+
+import type { Scope } from '@sentry/browser';
+
+sentryTest('Flag evaluations in forked scopes are stored separately.', async ({ getLocalTestUrl, page }) => {
+  if (shouldSkipFeatureFlagsTest()) {
+    sentryTest.skip();
+  }
+
+  await page.route('https://dsn.ingest.sentry.io/**/*', route => {
+    return route.fulfill({
+      status: 200,
+      contentType: 'application/json',
+      body: JSON.stringify({ id: 'test-id' }),
+    });
+  });
+
+  const url = await getLocalTestUrl({ testDir: __dirname, skipDsnRouteHandler: true });
+  await page.goto(url);
+
+  const forkedReqPromise = waitForErrorRequest(page, event => !!event.tags && event.tags.isForked === true);
+  const mainReqPromise = waitForErrorRequest(page, event => !!event.tags && event.tags.isForked === false);
+
+  await page.evaluate(() => {
+    const Sentry = (window as any).Sentry;
+    const errorButton = document.querySelector('#error') as HTMLButtonElement;
+    const unleash = new (window as any).UnleashClient();
+
+    unleash.isEnabled('strFeat');
+
+    Sentry.withScope((scope: Scope) => {
+      unleash.isEnabled('disabledFeat');
+      unleash.isEnabled('strFeat');
+      scope.setTag('isForked', true);
+      if (errorButton) {
+        errorButton.click();
+      }
+    });
+
+    unleash.isEnabled('noPayloadFeat');
+    Sentry.getCurrentScope().setTag('isForked', false);
+    errorButton.click();
+    return true;
+  });
+
+  const forkedReq = await forkedReqPromise;
+  const forkedEvent = envelopeRequestParser(forkedReq);
+
+  const mainReq = await mainReqPromise;
+  const mainEvent = envelopeRequestParser(mainReq);
+
+  expect(forkedEvent.contexts?.flags?.values).toEqual([
+    { flag: 'disabledFeat', result: false },
+    { flag: 'strFeat', result: true },
+  ]);
+
+  expect(mainEvent.contexts?.flags?.values).toEqual([
+    { flag: 'strFeat', result: true },
+    { flag: 'noPayloadFeat', result: true },
+  ]);
+});
diff --git a/packages/browser/src/integrations/featureFlags/unleash/integration.ts b/packages/browser/src/integrations/featureFlags/unleash/integration.ts
index c451afb831ba..c180cc101052 100644
--- a/packages/browser/src/integrations/featureFlags/unleash/integration.ts
+++ b/packages/browser/src/integrations/featureFlags/unleash/integration.ts
@@ -5,6 +5,15 @@ import { DEBUG_BUILD } from '../../../debug-build';
 import { copyFlagsFromScopeToEvent, insertFlagToScope } from '../../../utils/featureFlags';
 import type { UnleashClient, UnleashClientClass } from './types';
 
+type UnleashIntegrationOptions = {
+  featureFlagClientClass?: UnleashClientClass;
+
+  /**
+   * @deprecated Use `featureFlagClientClass` instead.
+   */
+  unleashClientClass?: UnleashClientClass;
+};
+
 /**
  * Sentry integration for capturing feature flag evaluations from the Unleash SDK.
  *
@@ -17,19 +26,24 @@ import type { UnleashClient, UnleashClientClass } from './types';
  *
  * Sentry.init({
  *   dsn: '___PUBLIC_DSN___',
- *   integrations: [Sentry.unleashIntegration({unleashClientClass: UnleashClient})],
+ *   integrations: [Sentry.unleashIntegration({featureFlagClientClass: UnleashClient})],
  * });
  *
  * const unleash = new UnleashClient(...);
  * unleash.start();
  *
  * unleash.isEnabled('my-feature');
- * unleash.getVariant('other-feature');
  * Sentry.captureException(new Error('something went wrong'));
  * ```
  */
 export const unleashIntegration = defineIntegration(
-  ({ unleashClientClass }: { unleashClientClass: UnleashClientClass }) => {
+  // eslint-disable-next-line deprecation/deprecation
+  ({ featureFlagClientClass, unleashClientClass }: UnleashIntegrationOptions) => {
+    const _unleashClientClass = featureFlagClientClass ? featureFlagClientClass : unleashClientClass;
+    if (!_unleashClientClass) {
+      throw new Error('featureFlagClientClass option is required');
+    }
+
     return {
       name: 'Unleash',
 
@@ -38,7 +52,7 @@ export const unleashIntegration = defineIntegration(
       },
 
       setupOnce() {
-        const unleashClientPrototype = unleashClientClass.prototype as UnleashClient;
+        const unleashClientPrototype = _unleashClientClass.prototype as UnleashClient;
         fill(unleashClientPrototype, 'isEnabled', _wrappedIsEnabled);
       },
     };
diff --git a/packages/browser/test/integrations/featureFlags/unleash.test.ts b/packages/browser/test/integrations/featureFlags/unleash.test.ts
new file mode 100644
index 000000000000..659d90fd9b03
--- /dev/null
+++ b/packages/browser/test/integrations/featureFlags/unleash.test.ts
@@ -0,0 +1,7 @@
+import { unleashIntegration } from '../../../src';
+
+describe('Unleash', () => {
+  it('Throws error if given empty options', () => {
+    expect(() => unleashIntegration({})).toThrow('featureFlagClientClass option is required');
+  });
+});