diff --git a/.size-limit.js b/.size-limit.js
index 761905a49ef3..eedacb4819bd 100644
--- a/.size-limit.js
+++ b/.size-limit.js
@@ -82,7 +82,7 @@ module.exports = [
     path: 'packages/browser/build/npm/esm/prod/index.js',
     import: createImport('init', 'browserTracingIntegration', 'replayIntegration', 'replayCanvasIntegration'),
     gzip: true,
-    limit: '85.55 KB',
+    limit: '86 KB',
   },
   {
     name: '@sentry/browser (incl. Tracing, Replay, Feedback)',
@@ -103,7 +103,7 @@ module.exports = [
     path: 'packages/browser/build/npm/esm/prod/index.js',
     import: createImport('init', 'sendFeedback'),
     gzip: true,
-    limit: '31 KB',
+    limit: '32 KB',
   },
   {
     name: '@sentry/browser (incl. FeedbackAsync)',
@@ -148,7 +148,7 @@ module.exports = [
     import: createImport('init', 'ErrorBoundary', 'reactRouterV6BrowserTracingIntegration'),
     ignore: ['react/jsx-runtime'],
     gzip: true,
-    limit: '44.5 KB',
+    limit: '45 KB',
   },
   // Vue SDK (ESM)
   {
@@ -163,7 +163,7 @@ module.exports = [
     path: 'packages/vue/build/esm/index.js',
     import: createImport('init', 'browserTracingIntegration'),
     gzip: true,
-    limit: '44.1 KB',
+    limit: '45 KB',
   },
   // Svelte SDK (ESM)
   {
@@ -171,20 +171,20 @@ module.exports = [
     path: 'packages/svelte/build/esm/index.js',
     import: createImport('init'),
     gzip: true,
-    limit: '25.5 KB',
+    limit: '26 KB',
   },
   // Browser CDN bundles
   {
     name: 'CDN Bundle',
     path: createCDNPath('bundle.min.js'),
     gzip: true,
-    limit: '28 KB',
+    limit: '28.5 KB',
   },
   {
     name: 'CDN Bundle (incl. Tracing)',
     path: createCDNPath('bundle.tracing.min.js'),
     gzip: true,
-    limit: '43 KB',
+    limit: '43.5 KB',
   },
   {
     name: 'CDN Bundle (incl. Logs, Metrics)',
diff --git a/packages/core/src/client.ts b/packages/core/src/client.ts
index 1ed447ab802d..e9e3c03538f7 100644
--- a/packages/core/src/client.ts
+++ b/packages/core/src/client.ts
@@ -34,6 +34,7 @@ import type { SeverityLevel } from './types-hoist/severity';
 import type { Span, SpanAttributes, SpanContextData, SpanJSON } from './types-hoist/span';
 import type { StartSpanOptions } from './types-hoist/startSpanOptions';
 import type { Transport, TransportMakeRequestResponse } from './types-hoist/transport';
+import { isStreamedBeforeSendSpanCallback } from './utils/beforeSendSpan';
 import { createClientReportEnvelope } from './utils/clientreport';
 import { debug } from './utils/debug-logger';
 import { dsnToString, makeDsn } from './utils/dsn';
@@ -1498,7 +1499,9 @@ function processBeforeSend(
   event: Event,
   hint: EventHint,
 ): PromiseLike<Event | null> | Event | null {
-  const { beforeSend, beforeSendTransaction, beforeSendSpan, ignoreSpans } = options;
+  const { beforeSend, beforeSendTransaction, ignoreSpans } = options;
+  const beforeSendSpan = !isStreamedBeforeSendSpanCallback(options.beforeSendSpan) && options.beforeSendSpan;
+
   let processedEvent = event;
 
   if (isErrorEvent(processedEvent) && beforeSend) {
diff --git a/packages/core/src/envelope.ts b/packages/core/src/envelope.ts
index 875056890e0e..c7a46359260f 100644
--- a/packages/core/src/envelope.ts
+++ b/packages/core/src/envelope.ts
@@ -18,6 +18,7 @@ import type { Event } from './types-hoist/event';
 import type { SdkInfo } from './types-hoist/sdkinfo';
 import type { SdkMetadata } from './types-hoist/sdkmetadata';
 import type { Session, SessionAggregates } from './types-hoist/session';
+import { isStreamedBeforeSendSpanCallback } from './utils/beforeSendSpan';
 import { dsnToString } from './utils/dsn';
 import {
   createEnvelope,
@@ -152,7 +153,7 @@ export function createSpanEnvelope(spans: [SentrySpan, ...SentrySpan[]], client?
   const convertToSpanJSON = beforeSendSpan
     ? (span: SentrySpan) => {
         const spanJson = spanToJSON(span);
-        const processedSpan = beforeSendSpan(spanJson);
+        const processedSpan = !isStreamedBeforeSendSpanCallback(beforeSendSpan) ? beforeSendSpan(spanJson) : spanJson;
 
         if (!processedSpan) {
           showSpanDropWarning();
diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index b05934465dfb..9968a4489c08 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -67,6 +67,7 @@ export { prepareEvent } from './utils/prepareEvent';
 export type { ExclusiveEventHintOrCaptureContext } from './utils/prepareEvent';
 export { createCheckInEnvelope } from './checkin';
 export { hasSpansEnabled } from './utils/hasSpansEnabled';
+export { withStreamedSpan } from './utils/beforeSendSpan';
 export { isSentryRequestUrl } from './utils/isSentryRequestUrl';
 export { handleCallbackErrors } from './utils/handleCallbackErrors';
 export { parameterize, fmt } from './utils/parameterize';
diff --git a/packages/core/src/types-hoist/options.ts b/packages/core/src/types-hoist/options.ts
index 9f8baca5b428..02d32bfb9fe0 100644
--- a/packages/core/src/types-hoist/options.ts
+++ b/packages/core/src/types-hoist/options.ts
@@ -6,7 +6,7 @@ import type { Log } from './log';
 import type { Metric } from './metric';
 import type { TracesSamplerSamplingContext } from './samplingcontext';
 import type { SdkMetadata } from './sdkmetadata';
-import type { SpanJSON } from './span';
+import type { SpanJSON, StreamedSpanJSON } from './span';
 import type { StackLineParser, StackParser } from './stacktrace';
 import type { TracePropagationTargets } from './tracing';
 import type { BaseTransportOptions, Transport } from './transport';
@@ -500,6 +500,14 @@ export interface ClientOptions<TO extends BaseTransportOptions = BaseTransportOp
    */
   strictTraceContinuation?: boolean;
 
+  /**
+   * The trace lifecycle, determining whether spans are sent statically when the entire local span tree is complete,
+   * or streamed in batches, following interval- and action-based triggers.
+   *
+   * @default 'static'
+   */
+  traceLifecycle?: 'static' | 'stream';
+
   /**
    * The organization ID for your Sentry project.
    *
@@ -579,11 +587,14 @@ export interface ClientOptions<TO extends BaseTransportOptions = BaseTransportOp
   /**
    * This function can be defined to modify a child span before it's sent.
    *
+   * When using `traceLifecycle: 'stream'`, wrap your callback with {@link withStreamedSpan}
+   * to receive and return {@link StreamedSpanJSON} instead.
+   *
    * @param span The span generated by the SDK.
    *
    * @returns The modified span payload that will be sent.
    */
-  beforeSendSpan?: (span: SpanJSON) => SpanJSON;
+  beforeSendSpan?: ((span: SpanJSON) => SpanJSON) | BeforeSendStramedSpanCallback;
 
   /**
    * An event-processing callback for transaction events, guaranteed to be invoked after all other event
@@ -615,6 +626,19 @@ export interface ClientOptions<TO extends BaseTransportOptions = BaseTransportOp
   beforeBreadcrumb?: (breadcrumb: Breadcrumb, hint?: BreadcrumbHint) => Breadcrumb | null;
 }
 
+/**
+ * A callback for processing streamed spans before they are sent.
+ *
+ * @see {@link StreamedSpanJSON} for the streamed span format used with `traceLifecycle: 'stream'`
+ */
+export type BeforeSendStramedSpanCallback = ((span: StreamedSpanJSON) => StreamedSpanJSON) & {
+  /**
+   * When true, indicates this callback is designed to handle the {@link StreamedSpanJSON} format
+   * used with `traceLifecycle: 'stream'`. Set this by wrapping your callback with `withStreamedSpan`.
+   */
+  _streamed?: true;
+};
+
 /** Base configuration options for every SDK. */
 export interface CoreOptions<TO extends BaseTransportOptions = BaseTransportOptions>
   extends Omit<Partial<ClientOptions<TO>>, 'integrations' | 'transport' | 'stackParser'> {
diff --git a/packages/core/src/utils/beforeSendSpan.ts b/packages/core/src/utils/beforeSendSpan.ts
new file mode 100644
index 000000000000..68c4576d179d
--- /dev/null
+++ b/packages/core/src/utils/beforeSendSpan.ts
@@ -0,0 +1,41 @@
+import type { BeforeSendStramedSpanCallback, ClientOptions } from '../types-hoist/options';
+import type { StreamedSpanJSON } from '../types-hoist/span';
+import { addNonEnumerableProperty } from './object';
+
+/**
+ * A wrapper to use the new span format in your `beforeSendSpan` callback.
+ *
+ * When using `traceLifecycle: 'stream'`, wrap your callback with this function
+ * to receive and return {@link StreamedSpanJSON} instead of the standard {@link SpanJSON}.
+ *
+ * @example
+ *
+ * Sentry.init({
+ *   traceLifecycle: 'stream',
+ *   beforeSendSpan: withStreamedSpan((span) => {
+ *     // span is of type StreamedSpanJSON
+ *     return span;
+ *   }),
+ * });
+ *
+ * @param callback - The callback function that receives and returns a {@link StreamedSpanJSON}.
+ * @returns A callback that is compatible with the `beforeSendSpan` option when using `traceLifecycle: 'stream'`.
+ */
+export function withStreamedSpan(
+  callback: (span: StreamedSpanJSON) => StreamedSpanJSON,
+): BeforeSendStramedSpanCallback {
+  addNonEnumerableProperty(callback, '_streamed', true);
+  return callback;
+}
+
+/**
+ * Typesafe check to identify if a `beforeSendSpan` callback expects the streamed span JSON format.
+ *
+ * @param callback - The `beforeSendSpan` callback to check.
+ * @returns `true` if the callback was wrapped with {@link withStreamedSpan}.
+ */
+export function isStreamedBeforeSendSpanCallback(
+  callback: ClientOptions['beforeSendSpan'],
+): callback is BeforeSendStramedSpanCallback {
+  return !!callback && '_streamed' in callback && !!callback._streamed;
+}
diff --git a/packages/core/test/lib/utils/beforeSendSpan.test.ts b/packages/core/test/lib/utils/beforeSendSpan.test.ts
new file mode 100644
index 000000000000..5e5bdc566889
--- /dev/null
+++ b/packages/core/test/lib/utils/beforeSendSpan.test.ts
@@ -0,0 +1,26 @@
+import { describe, expect, it, vi } from 'vitest';
+import { withStreamedSpan } from '../../../src';
+import { isStreamedBeforeSendSpanCallback } from '../../../src/utils/beforeSendSpan';
+
+describe('beforeSendSpan for span streaming', () => {
+  describe('withStreamedSpan', () => {
+    it('should be able to modify the span', () => {
+      const beforeSendSpan = vi.fn();
+      const wrapped = withStreamedSpan(beforeSendSpan);
+      expect(wrapped._streamed).toBe(true);
+    });
+  });
+
+  describe('isStreamedBeforeSendSpanCallback', () => {
+    it('returns true if the callback is wrapped with withStreamedSpan', () => {
+      const beforeSendSpan = vi.fn();
+      const wrapped = withStreamedSpan(beforeSendSpan);
+      expect(isStreamedBeforeSendSpanCallback(wrapped)).toBe(true);
+    });
+
+    it('returns false if the callback is not wrapped with withStreamedSpan', () => {
+      const beforeSendSpan = vi.fn();
+      expect(isStreamedBeforeSendSpanCallback(beforeSendSpan)).toBe(false);
+    });
+  });
+});