diff --git a/include/aws/http/private/h1_stream.h b/include/aws/http/private/h1_stream.h
index df1446ec..8b210c8b 100644
--- a/include/aws/http/private/h1_stream.h
+++ b/include/aws/http/private/h1_stream.h
@@ -117,6 +117,7 @@ struct aws_h1_stream *aws_h1_stream_new_request(
 struct aws_h1_stream *aws_h1_stream_new_request_handler(const struct aws_http_request_handler_options *options);
 
 int aws_h1_stream_activate(struct aws_http_stream *stream);
+void aws_h1_stream_cancel(struct aws_http_stream *stream, int error_code);
 
 int aws_h1_stream_send_response(struct aws_h1_stream *stream, struct aws_http_message *response);
 
diff --git a/include/aws/http/private/request_response_impl.h b/include/aws/http/private/request_response_impl.h
index 0a620b7f..acc5d9dd 100644
--- a/include/aws/http/private/request_response_impl.h
+++ b/include/aws/http/private/request_response_impl.h
@@ -17,6 +17,7 @@ struct aws_http_stream_vtable {
     void (*destroy)(struct aws_http_stream *stream);
     void (*update_window)(struct aws_http_stream *stream, size_t increment_size);
     int (*activate)(struct aws_http_stream *stream);
+    void (*cancel)(struct aws_http_stream *stream, int error_code);
 
     int (*http1_write_chunk)(struct aws_http_stream *http1_stream, const struct aws_http1_chunk_options *options);
     int (*http1_add_trailer)(struct aws_http_stream *http1_stream, const struct aws_http_headers *trailing_headers);
diff --git a/include/aws/http/request_response.h b/include/aws/http/request_response.h
index 878dbaf3..3f25fdd2 100644
--- a/include/aws/http/request_response.h
+++ b/include/aws/http/request_response.h
@@ -1109,6 +1109,18 @@ void aws_http_stream_update_window(struct aws_http_stream *stream, size_t increm
 AWS_HTTP_API
 uint32_t aws_http_stream_get_id(const struct aws_http_stream *stream);
 
+/**
+ * Cancel the stream in flight.
+ * For HTTP/1.1 streams, it's equivalent to closing the connection.
+ * For HTTP/2 streams, it's equivalent to calling reset on the stream with `AWS_HTTP2_ERR_CANCEL`.
+ *
+ * the stream will complete with the error code provided, unless the stream is
+ * already completing for other reasons, or the stream is not activated,
+ * in which case this call will have no impact.
+ */
+AWS_HTTP_API
+void aws_http_stream_cancel(struct aws_http_stream *stream, int error_code);
+
 /**
  * Reset the HTTP/2 stream (HTTP/2 only).
  * Note that if the stream closes before this async call is fully processed, the RST_STREAM frame will not be sent.
diff --git a/source/h1_connection.c b/source/h1_connection.c
index d04e844a..903cf038 100644
--- a/source/h1_connection.c
+++ b/source/h1_connection.c
@@ -388,6 +388,34 @@ int aws_h1_stream_activate(struct aws_http_stream *stream) {
     return AWS_OP_SUCCESS;
 }
 
+void aws_h1_stream_cancel(struct aws_http_stream *stream, int error_code) {
+    struct aws_h1_stream *h1_stream = AWS_CONTAINER_OF(stream, struct aws_h1_stream, base);
+    struct aws_http_connection *base_connection = stream->owning_connection;
+    struct aws_h1_connection *connection = AWS_CONTAINER_OF(base_connection, struct aws_h1_connection, base);
+
+    { /* BEGIN CRITICAL SECTION */
+        aws_h1_connection_lock_synced_data(connection);
+        if (h1_stream->synced_data.api_state != AWS_H1_STREAM_API_STATE_ACTIVE ||
+            connection->synced_data.is_open == false) {
+            /* Not active, nothing to cancel. */
+            aws_h1_connection_unlock_synced_data(connection);
+            AWS_LOGF_DEBUG(AWS_LS_HTTP_STREAM, "id=%p: Stream not active, nothing to cancel.", (void *)stream);
+            return;
+        }
+
+        aws_h1_connection_unlock_synced_data(connection);
+    } /* END CRITICAL SECTION */
+    AWS_LOGF_INFO(
+        AWS_LS_HTTP_CONNECTION,
+        "id=%p: Connection shutting down due to stream=%p cancelled with error code %d (%s).",
+        (void *)&connection->base,
+        (void *)stream,
+        error_code,
+        aws_error_name(error_code));
+
+    s_stop(connection, false /*stop_reading*/, false /*stop_writing*/, true /*schedule_shutdown*/, error_code);
+}
+
 struct aws_http_stream *s_make_request(
     struct aws_http_connection *client_connection,
     const struct aws_http_make_request_options *options) {
diff --git a/source/h1_stream.c b/source/h1_stream.c
index 0066ff69..ef8f086b 100644
--- a/source/h1_stream.c
+++ b/source/h1_stream.c
@@ -329,6 +329,7 @@ static const struct aws_http_stream_vtable s_stream_vtable = {
     .destroy = s_stream_destroy,
     .update_window = s_stream_update_window,
     .activate = aws_h1_stream_activate,
+    .cancel = aws_h1_stream_cancel,
     .http1_write_chunk = s_stream_write_chunk,
     .http1_add_trailer = s_stream_add_trailer,
     .http2_reset_stream = NULL,
diff --git a/source/h2_stream.c b/source/h2_stream.c
index 3ce23752..6d8336bf 100644
--- a/source/h2_stream.c
+++ b/source/h2_stream.c
@@ -27,12 +27,17 @@ static int s_stream_write_data(
 
 static void s_stream_cross_thread_work_task(struct aws_channel_task *task, void *arg, enum aws_task_status status);
 static struct aws_h2err s_send_rst_and_close_stream(struct aws_h2_stream *stream, struct aws_h2err stream_error);
-static int s_stream_reset_stream_internal(struct aws_http_stream *stream_base, struct aws_h2err stream_error);
+static int s_stream_reset_stream_internal(
+    struct aws_http_stream *stream_base,
+    struct aws_h2err stream_error,
+    bool cancelling);
+static void s_stream_cancel(struct aws_http_stream *stream, int error_code);
 
 struct aws_http_stream_vtable s_h2_stream_vtable = {
     .destroy = s_stream_destroy,
     .update_window = s_stream_update_window,
     .activate = aws_h2_stream_activate,
+    .cancel = s_stream_cancel,
     .http1_write_chunk = NULL,
     .http2_reset_stream = s_stream_reset_stream,
     .http2_get_received_error_code = s_stream_get_received_error_code,
@@ -526,12 +531,16 @@ static void s_stream_update_window(struct aws_http_stream *stream_base, size_t i
             .h2_code = AWS_HTTP2_ERR_INTERNAL_ERROR,
         };
         /* Only when stream is not initialized reset will fail. So, we can assert it to be succeed. */
-        AWS_FATAL_ASSERT(s_stream_reset_stream_internal(stream_base, stream_error) == AWS_OP_SUCCESS);
+        AWS_FATAL_ASSERT(
+            s_stream_reset_stream_internal(stream_base, stream_error, false /*cancelling*/) == AWS_OP_SUCCESS);
     }
     return;
 }
 
-static int s_stream_reset_stream_internal(struct aws_http_stream *stream_base, struct aws_h2err stream_error) {
+static int s_stream_reset_stream_internal(
+    struct aws_http_stream *stream_base,
+    struct aws_h2err stream_error,
+    bool cancelling) {
 
     struct aws_h2_stream *stream = AWS_CONTAINER_OF(stream_base, struct aws_h2_stream, base);
     struct aws_h2_connection *connection = s_get_h2_connection(stream);
@@ -553,21 +562,25 @@ static int s_stream_reset_stream_internal(struct aws_http_stream *stream_base, s
     } /* END CRITICAL SECTION */
 
     if (stream_is_init) {
+        if (cancelling) {
+            /* Not an error if we are just cancelling. */
+            AWS_LOGF_DEBUG(AWS_LS_HTTP_STREAM, "id=%p: Stream not in process, nothing to cancel.", (void *)stream);
+            return AWS_OP_SUCCESS;
+        }
         AWS_H2_STREAM_LOG(
             ERROR, stream, "Reset stream failed. Stream is in initialized state, please activate the stream first.");
         return aws_raise_error(AWS_ERROR_INVALID_STATE);
     }
+    if (reset_called) {
+        AWS_H2_STREAM_LOG(DEBUG, stream, "Reset stream ignored. Reset stream has been called already.");
+    }
+
     if (cross_thread_work_should_schedule) {
         AWS_H2_STREAM_LOG(TRACE, stream, "Scheduling stream cross-thread work task");
         /* increment the refcount of stream to keep it alive until the task runs */
         aws_atomic_fetch_add(&stream->base.refcount, 1);
         aws_channel_schedule_task_now(connection->base.channel_slot->channel, &stream->cross_thread_work_task);
-        return AWS_OP_SUCCESS;
     }
-    if (reset_called) {
-        AWS_H2_STREAM_LOG(DEBUG, stream, "Reset stream ignored. Reset stream has been called already.");
-    }
-
     return AWS_OP_SUCCESS;
 }
 
@@ -583,7 +596,16 @@ static int s_stream_reset_stream(struct aws_http_stream *stream_base, uint32_t h
         (void *)stream_base,
         aws_http2_error_code_to_str(http2_error),
         http2_error);
-    return s_stream_reset_stream_internal(stream_base, stream_error);
+    return s_stream_reset_stream_internal(stream_base, stream_error, false /*cancelling*/);
+}
+
+void s_stream_cancel(struct aws_http_stream *stream_base, int error_code) {
+    struct aws_h2err stream_error = {
+        .aws_code = error_code,
+        .h2_code = AWS_HTTP2_ERR_CANCEL,
+    };
+    s_stream_reset_stream_internal(stream_base, stream_error, true /*cancelling*/);
+    return;
 }
 
 static int s_stream_get_received_error_code(struct aws_http_stream *stream_base, uint32_t *out_http2_error) {
diff --git a/source/request_response.c b/source/request_response.c
index f76115f2..dbd5214e 100644
--- a/source/request_response.c
+++ b/source/request_response.c
@@ -1201,6 +1201,10 @@ uint32_t aws_http_stream_get_id(const struct aws_http_stream *stream) {
     return stream->id;
 }
 
+void aws_http_stream_cancel(struct aws_http_stream *stream, int error_code) {
+    stream->vtable->cancel(stream, error_code);
+}
+
 int aws_http2_stream_reset(struct aws_http_stream *http2_stream, uint32_t http2_error) {
     AWS_PRECONDITION(http2_stream);
     AWS_PRECONDITION(http2_stream->vtable);
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 7e61445d..06dc389f 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -143,6 +143,7 @@ add_test_case(h1_client_switching_protocols_fails_pending_requests)
 add_test_case(h1_client_switching_protocols_fails_subsequent_requests)
 add_test_case(h1_client_switching_protocols_requires_downstream_handler)
 add_test_case(h1_client_connection_close_before_request_finishes)
+add_test_case(h1_client_stream_cancel)
 add_test_case(h1_client_response_close_connection_before_request_finishes)
 add_test_case(h1_client_response_first_byte_timeout_connection)
 add_test_case(h1_client_response_first_byte_timeout_request_override)
@@ -475,6 +476,7 @@ add_test_case(h2_client_conn_failed_initial_settings_completed_not_invoked)
 add_test_case(h2_client_stream_reset_stream)
 add_test_case(h2_client_stream_reset_ignored_stream_closed)
 add_test_case(h2_client_stream_reset_failed_before_activate_called)
+add_test_case(h2_client_stream_cancel_stream)
 add_test_case(h2_client_stream_keeps_alive_for_cross_thread_task)
 add_test_case(h2_client_stream_get_received_reset_error_code)
 add_test_case(h2_client_stream_get_sent_reset_error_code)
diff --git a/tests/test_h1_client.c b/tests/test_h1_client.c
index de7751a8..19cf1f97 100644
--- a/tests/test_h1_client.c
+++ b/tests/test_h1_client.c
@@ -4236,6 +4236,62 @@ H1_CLIENT_TEST_CASE(h1_client_connection_close_before_request_finishes) {
     return AWS_OP_SUCCESS;
 }
 
+H1_CLIENT_TEST_CASE(h1_client_stream_cancel) {
+    (void)ctx;
+    struct tester tester;
+    ASSERT_SUCCESS(s_tester_init(&tester, allocator));
+
+    /* set up request whose body won't send immediately */
+    struct slow_body_sender body_sender;
+    AWS_ZERO_STRUCT(body_sender);
+    s_slow_body_sender_init(&body_sender);
+    struct aws_input_stream *body_stream = &body_sender.base;
+
+    struct aws_http_header headers[] = {
+        {
+            .name = aws_byte_cursor_from_c_str("Content-Length"),
+            .value = aws_byte_cursor_from_c_str("16"),
+        },
+    };
+
+    struct aws_http_message *request = aws_http_message_new_request(allocator);
+    ASSERT_NOT_NULL(request);
+    ASSERT_SUCCESS(aws_http_message_set_request_method(request, aws_byte_cursor_from_c_str("PUT")));
+    ASSERT_SUCCESS(aws_http_message_set_request_path(request, aws_byte_cursor_from_c_str("/plan.txt")));
+    ASSERT_SUCCESS(aws_http_message_add_header_array(request, headers, AWS_ARRAY_SIZE(headers)));
+    aws_http_message_set_body_stream(request, body_stream);
+
+    struct client_stream_tester stream_tester;
+    ASSERT_SUCCESS(s_stream_tester_init(&stream_tester, &tester, request));
+
+    /* send head of request */
+    testing_channel_run_currently_queued_tasks(&tester.testing_channel);
+
+    /* Ensure the request can be destroyed after request is sent */
+    aws_http_message_destroy(request);
+    aws_input_stream_release(body_stream);
+
+    /* Something absurd */
+    aws_http_stream_cancel(stream_tester.stream, AWS_ERROR_COND_VARIABLE_ERROR_UNKNOWN);
+    /* The second call will take not action */
+    aws_http_stream_cancel(stream_tester.stream, AWS_ERROR_SUCCESS);
+    /* Wait for channel to finish shutdown */
+    testing_channel_drain_queued_tasks(&tester.testing_channel);
+    /* check result, should not receive any body */
+    const char *expected = "PUT /plan.txt HTTP/1.1\r\n"
+                           "Content-Length: 16\r\n"
+                           "\r\n";
+    ASSERT_SUCCESS(testing_channel_check_written_messages_str(&tester.testing_channel, allocator, expected));
+
+    ASSERT_TRUE(stream_tester.complete);
+    ASSERT_INT_EQUALS(AWS_ERROR_COND_VARIABLE_ERROR_UNKNOWN, stream_tester.on_complete_error_code);
+
+    /* clean up */
+    client_stream_tester_clean_up(&stream_tester);
+    ASSERT_SUCCESS(s_tester_clean_up(&tester));
+    return AWS_OP_SUCCESS;
+}
+
 /* When response has `connection: close` any further request body should not be sent. */
 H1_CLIENT_TEST_CASE(h1_client_response_close_connection_before_request_finishes) {
     (void)ctx;
diff --git a/tests/test_h2_client.c b/tests/test_h2_client.c
index 74393188..093e89f9 100644
--- a/tests/test_h2_client.c
+++ b/tests/test_h2_client.c
@@ -4508,6 +4508,49 @@ TEST_CASE(h2_client_stream_reset_failed_before_activate_called) {
     return s_tester_clean_up();
 }
 
+TEST_CASE(h2_client_stream_cancel_stream) {
+    ASSERT_SUCCESS(s_tester_init(allocator, ctx));
+    /* get connection preface and acks out of the way */
+    ASSERT_SUCCESS(h2_fake_peer_send_connection_preface_default_settings(&s_tester.peer));
+    ASSERT_SUCCESS(h2_fake_peer_decode_messages_from_testing_channel(&s_tester.peer));
+    struct aws_http_message *request = aws_http2_message_new_request(allocator);
+    ASSERT_NOT_NULL(request);
+
+    struct aws_http_header request_headers_src[] = {
+        DEFINE_HEADER(":method", "GET"),
+        DEFINE_HEADER(":scheme", "https"),
+        DEFINE_HEADER(":path", "/"),
+    };
+    aws_http_message_add_header_array(request, request_headers_src, AWS_ARRAY_SIZE(request_headers_src));
+    struct aws_http_make_request_options request_options = {
+        .self_size = sizeof(request_options),
+        .request = request,
+    };
+
+    struct client_stream_tester stream_tester;
+    ASSERT_SUCCESS(s_stream_tester_init(&stream_tester, request));
+    testing_channel_drain_queued_tasks(&s_tester.testing_channel);
+
+    /* Cancel the request */
+    aws_http_stream_cancel(stream_tester.stream, AWS_ERROR_COND_VARIABLE_ERROR_UNKNOWN);
+    testing_channel_drain_queued_tasks(&s_tester.testing_channel);
+
+    ASSERT_TRUE(aws_http_connection_is_open(s_tester.connection));
+    ASSERT_TRUE(stream_tester.complete);
+    ASSERT_INT_EQUALS(AWS_ERROR_COND_VARIABLE_ERROR_UNKNOWN, stream_tester.on_complete_error_code);
+    /* validate that stream sent RST_STREAM */
+    ASSERT_SUCCESS(h2_fake_peer_decode_messages_from_testing_channel(&s_tester.peer));
+    struct h2_decoded_frame *rst_stream_frame =
+        h2_decode_tester_find_frame(&s_tester.peer.decode, AWS_H2_FRAME_T_RST_STREAM, 0, NULL);
+    /* But the error code is not the same as user was trying to send */
+    ASSERT_UINT_EQUALS(AWS_HTTP2_ERR_CANCEL, rst_stream_frame->error_code);
+
+    /* clean up */
+    aws_http_message_release(request);
+    client_stream_tester_clean_up(&stream_tester);
+    return s_tester_clean_up();
+}
+
 TEST_CASE(h2_client_stream_keeps_alive_for_cross_thread_task) {
 
     ASSERT_SUCCESS(s_tester_init(allocator, ctx));