diff --git a/infra/build/functions/fuzzbench.py b/infra/build/functions/fuzzbench.py
index 2f353cbf02c2..0936cb6debe8 100644
--- a/infra/build/functions/fuzzbench.py
+++ b/infra/build/functions/fuzzbench.py
@@ -34,6 +34,7 @@
 FUZZBENCH_PATH = '/fuzzbench'
 GCB_WORKSPACE_DIR = '/workspace'
 OOD_OUTPUT_CORPUS_DIR = f'{GCB_WORKSPACE_DIR}/ood_output_corpus'
+OOD_CRASHES_DIR = f'{GCB_WORKSPACE_DIR}/crashes'
 
 
 def get_engine_project_image_name(fuzzing_engine, project):
@@ -129,16 +130,14 @@ def get_build_fuzzers_steps(fuzzing_engine, project, env):
                                     project), '--file', engine_dockerfile_path,
       os.path.join(FUZZBENCH_PATH, 'fuzzers')
   ]
-  engine_step = [
-      {
-          'name': 'gcr.io/cloud-builders/docker',
-          'args': build_args,
-          'volumes': [{
-              'name': 'fuzzbench_path',
-              'path': FUZZBENCH_PATH,
-          }],
-      },
-  ]
+  engine_step = {
+      'name': 'gcr.io/cloud-builders/docker',
+      'args': build_args,
+      'volumes': [{
+          'name': 'fuzzbench_path',
+          'path': FUZZBENCH_PATH,
+      }],
+  }
   steps.append(engine_step)
 
   compile_project_step = {
@@ -240,7 +239,7 @@ def get_build_ood_image_steps(fuzzing_engine, project, env_dict):
           'build', '--tag', ood_image, '--file', fuzzer_runtime_dockerfile_path,
           os.path.join(GCB_WORKSPACE_DIR + FUZZBENCH_PATH, 'fuzzers')
       ]
-  },
+  }
   steps.append(build_runtime_step)
 
   oss_fuzz_on_demand_dockerfile_path = f'{GCB_WORKSPACE_DIR}/oss-fuzz/infra/build/functions/ood.Dockerfile'
@@ -310,16 +309,15 @@ def get_extract_crashes_steps(fuzzing_engine, project, env_dict):
   }
   steps.append(download_libfuzzer_build_step)
 
-  crashes_dir = f'{GCB_WORKSPACE_DIR}/crashes/'
   extract_crashes_step = {
       'name':
           get_engine_project_image_name(fuzzing_engine, project),
       'args': [
           'bash', '-c', f'unzip {libfuzzer_build_dir}{build_filename} '
-          f'-d {libfuzzer_build_dir} && mkdir -p {crashes_dir} && '
+          f'-d {libfuzzer_build_dir} && mkdir -p {OOD_CRASHES_DIR} && '
           f'{libfuzzer_build_dir}{env_dict["FUZZ_TARGET"]} {OOD_OUTPUT_CORPUS_DIR} '
-          f'-runs=0 -artifact_prefix={crashes_dir}; '
-          f'echo "\nCrashes found by OOD:" && ls {crashes_dir} '
+          f'-runs=0 -artifact_prefix={OOD_CRASHES_DIR}/; '
+          f'echo "\nCrashes found by OOD:" && ls {OOD_CRASHES_DIR} '
       ],
   }
   steps.append(extract_crashes_step)
@@ -327,6 +325,38 @@ def get_extract_crashes_steps(fuzzing_engine, project, env_dict):
   return steps
 
 
+def get_upload_testcase_steps(project, env_dict):
+  """Returns the build steps to upload a testcase in the ClusterFuzz External
+  upload testcase endpoint."""
+  steps = []
+
+  access_token_file_path = f'{GCB_WORKSPACE_DIR}/at.txt'
+  get_access_token_step = {
+      'name':
+          'google/cloud-sdk',
+      'args': [
+          'bash', '-c',
+          f'gcloud auth print-access-token > {access_token_file_path}'
+      ]
+  }
+  steps.append(get_access_token_step)
+
+  upload_testcase_script_path = f'{GCB_WORKSPACE_DIR}/oss-fuzz/infra/build/functions/ood_upload_testcase.py'
+  job_name = f'libfuzzer_asan_{project.name}'
+  target_name = f'{project.name}_{env_dict["FUZZ_TARGET"]}'
+  upload_testcase_step = {
+      'name':
+          'python:3.8',
+      'args': [
+          'python3', upload_testcase_script_path, OOD_CRASHES_DIR, job_name,
+          target_name, access_token_file_path
+      ]
+  }
+  steps.append(upload_testcase_step)
+
+  return steps
+
+
 def get_build_steps(  # pylint: disable=too-many-locals, too-many-arguments
     project_name, project_yaml, dockerfile_lines, config):
   """Returns build steps for project."""
@@ -349,6 +379,7 @@ def get_build_steps(  # pylint: disable=too-many-locals, too-many-arguments
   steps += get_push_and_run_ood_image_steps(config.fuzzing_engine, project,
                                             env_dict)
   steps += get_extract_crashes_steps(config.fuzzing_engine, project, env_dict)
+  steps += get_upload_testcase_steps(project, env_dict)
 
   return steps
 
diff --git a/infra/build/functions/ood_upload_testcase.py b/infra/build/functions/ood_upload_testcase.py
new file mode 100644
index 000000000000..eb34fdbd0d2d
--- /dev/null
+++ b/infra/build/functions/ood_upload_testcase.py
@@ -0,0 +1,100 @@
+#!/usr/bin/env python3
+#
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+################################################################################
+"""Upload OSS-Fuzz on Demand testcases."""
+
+import json
+import logging
+import os
+import sys
+import subprocess
+
+try:
+  import requests
+except ImportError:
+  print("requests library not found. Installing...")
+  subprocess.check_call([sys.executable, "-m", "pip", "install", "requests"])
+  import requests
+
+POST_URL = 'https://oss-fuzz.com/upload-testcase/upload-oauth'
+
+
+def get_access_token(access_token_path):
+  """Returns the ACCESS_TOKEN for upload testcase requests"""
+  with open(access_token_path, 'r') as f:
+    line = f.readline()
+    return line.strip()
+
+
+def get_headers(access_token_path):
+  """Returns the headers required to upload testcase requests"""
+  access_token = get_access_token(access_token_path)
+  return {
+      'Authorization': 'Bearer ' + access_token,
+  }
+
+
+def upload_testcase(upload_url, testcase_path, job, target, access_token_path):
+  """Make an upload testcase request."""
+  files = {
+      'file': open(testcase_path, 'rb'),
+  }
+  data = {
+      'job': job,
+      'target': target,
+  }
+  try:
+    resp = requests.post(upload_url,
+                         files=files,
+                         data=data,
+                         headers=get_headers(access_token_path))
+    resp.raise_for_status()
+    result = json.loads(resp.text)
+    print('Upload succeeded. Testcase ID is', result['id'])
+  except:
+    print('Failed to upload with status', resp.status_code)
+    print(resp.text)
+
+
+def get_file_path(dir_path):
+  """Returns the path of a file inside 'dir_path'. Returns None if there are no
+  files inside the the given directory."""
+  files = []
+  for entry in os.scandir(dir_path):
+    if entry.is_file():
+      return f'{dir_path}/{entry.name}'
+  return None
+
+
+def main():
+  """Upload an OSS-Fuzz on Demand testcase."""
+  testcase_dir_path = sys.argv[1]
+  job = sys.argv[2]
+  target = sys.argv[3]
+  access_token_path = sys.argv[4]
+  testcase_path = get_file_path(testcase_dir_path)
+
+  if not testcase_path:
+    print('OSS-Fuzz on Demand did not find any crashes.')
+  else:
+    upload_testcase(POST_URL, testcase_path, job, target, access_token_path)
+
+  return 0
+
+
+if __name__ == '__main__':
+  main()
diff --git a/infra/build/functions/ood_upload_testcase_test.py b/infra/build/functions/ood_upload_testcase_test.py
new file mode 100644
index 000000000000..fa59e0d44eee
--- /dev/null
+++ b/infra/build/functions/ood_upload_testcase_test.py
@@ -0,0 +1,69 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+################################################################################
+"""Tests for ood_upload_testcase_test.py."""
+
+import os
+import shutil
+import tempfile
+import unittest
+from unittest import mock
+
+import ood_upload_testcase
+
+
+class GetFilePath(unittest.TestCase):
+  """Tests for get_file_path."""
+
+  def setUp(self):
+    """Set tem_dir attribute"""
+    self.temp_dir = tempfile.mkdtemp()
+
+  def tearDown(self):
+    """Remove temp_dir after tests"""
+    shutil.rmtree(self.temp_dir)
+
+  def test_no_files(self):
+    """Test for empty directory"""
+    self.assertIsNone(ood_upload_testcase.get_file_path(self.temp_dir))
+
+  def test_single_file(self):
+    """Test for single file"""
+    file_name = 'test_file.txt'
+    file_path = os.path.join(self.temp_dir, file_name)
+    open(file_path, 'w').close()
+    self.assertEqual(ood_upload_testcase.get_file_path(self.temp_dir),
+                     file_path)
+
+  def test_multiple_files(self):
+    """Test for multiple files"""
+    file_names = ['file1.txt', 'file2.csv', 'data.json']
+    file_paths = []
+    for name in file_names:
+      file_path = os.path.join(self.temp_dir, name)
+      file_paths.append(file_path)
+      open(file_path, 'w').close()
+    self.assertIn(ood_upload_testcase.get_file_path(self.temp_dir), file_paths)
+
+  def test_with_subdirectory(self):
+    """Test for directory with subdirectory"""
+    os.makedirs(os.path.join(self.temp_dir, 'subdir'))
+    self.assertIsNone(ood_upload_testcase.get_file_path(self.temp_dir))
+
+    file_name = 'test_file.txt'
+    file_path = os.path.join(self.temp_dir, file_name)
+    open(file_path, 'w').close()
+    self.assertEqual(ood_upload_testcase.get_file_path(self.temp_dir),
+                     file_path)