diff --git a/packages/core/src/integrations/supabase.ts b/packages/core/src/integrations/supabase.ts
index 64a75359bcbd..605228376354 100644
--- a/packages/core/src/integrations/supabase.ts
+++ b/packages/core/src/integrations/supabase.ts
@@ -11,6 +11,7 @@ import { defineIntegration } from '../integration';
 import { SEMANTIC_ATTRIBUTE_SENTRY_OP, SEMANTIC_ATTRIBUTE_SENTRY_ORIGIN } from '../semanticAttributes';
 import { setHttpStatus, SPAN_STATUS_ERROR, SPAN_STATUS_OK, startSpan } from '../tracing';
 import type { IntegrationFn } from '../types/integration';
+import type { WebFetchHeaders } from '../types/webfetchapi';
 import { debug } from '../utils/debug-logger';
 import { isObjectLike, isPlainObject } from '../utils/is';
 import { addExceptionMechanism } from '../utils/misc';
@@ -84,9 +85,15 @@ export interface PostgRESTQueryBuilder {
   [key: string]: PostgRESTQueryOperationFn;
 }
 
+/**
+ * `postgrest-js` stores the request headers as a plain object up to v1.19.x and as a `Headers`
+ * instance from v2.74.0 on (shipped with `supabase-js` 2.74.0), so we have to handle both shapes.
+ */
+export type PostgRESTHeaders = Record<string, string> | WebFetchHeaders;
+
 export interface PostgRESTFilterBuilder {
   method: string;
-  headers: Record<string, string>;
+  headers: PostgRESTHeaders;
   url: URL;
   schema: string;
   body: any;
@@ -168,19 +175,42 @@ function hasMutationBodyForDescription(rawBody: unknown, plainBody: Record<strin
   return getMutationBodyPayloadForTelemetry(rawBody, plainBody) !== undefined;
 }
 
+/**
+ * Reads a header off a PostgREST builder, regardless of whether it holds a plain object or a
+ * `Headers` instance. Lookup is case-insensitive because `Headers` lower-cases all of its keys.
+ * @param headers - The request headers
+ * @param name - The header name to look up
+ * @returns The header value, or `undefined` if it is not set
+ */
+export function getHeader(headers: PostgRESTHeaders | undefined, name: string): string | undefined {
+  if (!headers) {
+    return undefined;
+  }
+
+  if (typeof (headers as WebFetchHeaders).get === 'function') {
+    return (headers as WebFetchHeaders).get(name) ?? undefined;
+  }
+
+  const plainHeaders = headers as Record<string, string>;
+  const lowerCaseName = name.toLowerCase();
+  const key = Object.keys(plainHeaders).find(headerName => headerName.toLowerCase() === lowerCaseName);
+
+  return key !== undefined ? plainHeaders[key] : undefined;
+}
+
 /**
  * Extracts the database operation type from the HTTP method and headers
  * @param method - The HTTP method of the request
  * @param headers - The request headers
  * @returns The database operation type ('select', 'insert', 'upsert', 'update', or 'delete')
  */
-export function extractOperation(method: string, headers: Record<string, string> = {}): string {
+export function extractOperation(method: string, headers: PostgRESTHeaders = {}): string {
   switch (method) {
     case 'GET': {
       return 'select';
     }
     case 'POST': {
-      if (headers['Prefer']?.includes('resolution=')) {
+      if (getHeader(headers, 'Prefer')?.includes('resolution=')) {
         return 'upsert';
       } else {
         return 'insert';
@@ -404,7 +434,7 @@ function instrumentPostgRESTFilterBuilder(
           'db.table': table,
           'db.schema': typedThis.schema,
           'db.url': typedThis.url.origin,
-          'db.sdk': typedThis.headers['X-Client-Info'],
+          'db.sdk': getHeader(typedThis.headers, 'X-Client-Info'),
           'db.system': 'postgresql',
           'db.operation': operation,
           [SEMANTIC_ATTRIBUTE_SENTRY_ORIGIN]: 'auto.db.supabase',
diff --git a/packages/core/test/lib/integrations/supabase.test.ts b/packages/core/test/lib/integrations/supabase.test.ts
index fef69305a6fd..d776b8a85c83 100644
--- a/packages/core/test/lib/integrations/supabase.test.ts
+++ b/packages/core/test/lib/integrations/supabase.test.ts
@@ -3,10 +3,15 @@ import * as breadcrumbModule from '../../../src/breadcrumbs';
 import * as exportsModule from '../../../src/exports';
 import {
   extractOperation,
+  getHeader,
   instrumentSupabaseClient,
   translateFiltersIntoMethods,
 } from '../../../src/integrations/supabase';
-import type { PostgRESTQueryBuilder, SupabaseClientInstance } from '../../../src/integrations/supabase';
+import type {
+  PostgRESTHeaders,
+  PostgRESTQueryBuilder,
+  SupabaseClientInstance,
+} from '../../../src/integrations/supabase';
 import { resolveDataCollectionOptions } from '../../../src/utils/data-collection/resolveDataCollectionOptions';
 
 const tracingMocks = vi.hoisted(() => ({
@@ -39,6 +44,8 @@ type CreateMockSupabaseClientOptions = {
   method?: string;
   url?: URL | string;
   body?: unknown;
+  /** Defaults to the plain-object shape used by `postgrest-js` v1. Pass a `Headers` instance to emulate v2. */
+  headers?: PostgRESTHeaders;
   /** When set, configures the mocked Sentry client's `dataCollection.databaseQueryData`. Omit to leave `getClient` to the test file `beforeEach`. */
   dataCollectionDatabaseQueryData?: boolean;
 };
@@ -67,10 +74,11 @@ function createMockSupabaseClient(resolveWith: unknown, options?: CreateMockSupa
         : new URL(options.url)
       : new URL(DEFAULT_MOCK_SUPABASE_REST_URL);
   const body = options?.body;
+  const headers = options?.headers ?? { 'X-Client-Info': 'supabase-js/2.0.0' };
 
   class MockPostgRESTFilterBuilder {
     method = method;
-    headers: Record<string, string> = { 'X-Client-Info': 'supabase-js/2.0.0' };
+    headers: PostgRESTHeaders = headers;
     url = requestUrl;
     schema = 'public';
     body = body;
@@ -116,6 +124,28 @@ describe('Supabase Integration', () => {
     currentScopesMocks.getClient.mockReturnValue(undefined);
   });
 
+  describe('getHeader', () => {
+    it('reads a header off a plain object', () => {
+      expect(getHeader({ 'X-Client-Info': 'supabase-js/2.0.0' }, 'X-Client-Info')).toBe('supabase-js/2.0.0');
+    });
+
+    it('reads a header off a Headers instance', () => {
+      expect(getHeader(new Headers({ 'X-Client-Info': 'supabase-js/2.112.0' }), 'X-Client-Info')).toBe(
+        'supabase-js/2.112.0',
+      );
+    });
+
+    it('looks up plain object headers case-insensitively', () => {
+      expect(getHeader({ prefer: 'resolution=merge-duplicates' }, 'Prefer')).toBe('resolution=merge-duplicates');
+    });
+
+    it('returns undefined for unset headers', () => {
+      expect(getHeader({ Prefer: 'count=exact' }, 'X-Client-Info')).toBeUndefined();
+      expect(getHeader(new Headers({ Prefer: 'count=exact' }), 'X-Client-Info')).toBeUndefined();
+      expect(getHeader(undefined, 'X-Client-Info')).toBeUndefined();
+    });
+  });
+
   describe('extractOperation', () => {
     it('returns select for GET', () => {
       expect(extractOperation('GET')).toBe('select');
@@ -129,6 +159,10 @@ describe('Supabase Integration', () => {
       expect(extractOperation('POST', { Prefer: 'resolution=merge-duplicates' })).toBe('upsert');
     });
 
+    it('returns upsert for POST with resolution header on a Headers instance', () => {
+      expect(extractOperation('POST', new Headers({ Prefer: 'resolution=merge-duplicates' }))).toBe('upsert');
+    });
+
     it('returns update for PATCH', () => {
       expect(extractOperation('PATCH')).toBe('update');
     });
@@ -433,4 +467,53 @@ describe('Supabase Integration', () => {
       expect(spanOptions.attributes['db.body']).toEqual([{ title: 'Test Todo' }]);
     });
   });
+
+  describe.each([
+    ['plain object headers', (init: Record<string, string>): PostgRESTHeaders => init],
+    ['Headers instance', (init: Record<string, string>): PostgRESTHeaders => new Headers(init)],
+  ])('%s', (_name, createHeaders) => {
+    beforeEach(() => {
+      vi.spyOn(breadcrumbModule, 'addBreadcrumb').mockImplementation(() => {});
+    });
+
+    afterEach(() => {
+      vi.restoreAllMocks();
+    });
+
+    it('sets db.sdk from X-Client-Info', async () => {
+      tracingMocks.startSpan.mockClear();
+      const client = createMockSupabaseClient(
+        { status: 200 },
+        { headers: createHeaders({ 'X-Client-Info': 'supabase-js/2.112.0' }) },
+      );
+      instrumentSupabaseClient(client);
+
+      await (client as any).from('todos').select().then();
+
+      const spanOptions = tracingMocks.startSpan.mock.calls[0]![0] as { attributes: Record<string, unknown> };
+      expect(spanOptions.attributes['db.sdk']).toBe('supabase-js/2.112.0');
+    });
+
+    it('detects upsert from the Prefer header', async () => {
+      tracingMocks.startSpan.mockClear();
+      const client = createMockSupabaseClient(
+        { status: 200 },
+        {
+          method: 'POST',
+          body: { title: 'Test Todo' },
+          headers: createHeaders({ Prefer: 'resolution=merge-duplicates' }),
+        },
+      );
+      instrumentSupabaseClient(client);
+
+      await (client as any).from('todos').upsert({}).then();
+
+      const spanOptions = tracingMocks.startSpan.mock.calls[0]![0] as {
+        name: string;
+        attributes: Record<string, unknown>;
+      };
+      expect(spanOptions.name).toMatch(/^upsert\(\.\.\.\)/);
+      expect(spanOptions.attributes['db.operation']).toBe('upsert');
+    });
+  });
 });