diff --git a/changelogs/fragments/187-fix-synchronize-become-user.yml b/changelogs/fragments/187-fix-synchronize-become-user.yml
new file mode 100644
index 0000000000..77d72e016e
--- /dev/null
+++ b/changelogs/fragments/187-fix-synchronize-become-user.yml
@@ -0,0 +1,4 @@
+---
+bugfixes:
+  - synchronize - use become_user when invoking rsync on remote with sudo
+    (https://github.com/ansible-collections/ansible.posix/issues/186).
diff --git a/plugins/action/synchronize.py b/plugins/action/synchronize.py
index ec71fe0ec9..2f0a6e0fad 100644
--- a/plugins/action/synchronize.py
+++ b/plugins/action/synchronize.py
@@ -367,7 +367,10 @@ def run(self, tmp=None, task_vars=None):
                 # If no rsync_path is set, become was originally set, and dest is
                 # remote then add privilege escalation here.
                 if self._play_context.become_method == 'sudo':
-                    rsync_path = 'sudo rsync'
+                    if self._play_context.become_user:
+                        rsync_path = 'sudo -u %s rsync' % self._play_context.become_user
+                    else:
+                        rsync_path = 'sudo rsync'
                 # TODO: have to add in the rest of the become methods here
 
             # We cannot use privilege escalation on the machine running the
diff --git a/tests/unit/plugins/action/fixtures/synchronize/basic_become/meta.yaml b/tests/unit/plugins/action/fixtures/synchronize/basic_become/meta.yaml
index 1ba3b4ab9b..8435735b67 100644
--- a/tests/unit/plugins/action/fixtures/synchronize/basic_become/meta.yaml
+++ b/tests/unit/plugins/action/fixtures/synchronize/basic_become/meta.yaml
@@ -25,7 +25,8 @@ asserts:
     - "self.execute_called"
     - "self.final_module_args['_local_rsync_path'] == 'rsync'"
     # this is a crucial aspect of this scenario ...
-    - "self.final_module_args['rsync_path'] == 'sudo rsync'"
+    # note: become_user None -> root
+    - "self.final_module_args['rsync_path'] == 'sudo -u root rsync'"
     - "self.final_module_args['src'] == '/tmp/deleteme'"
     - "self.final_module_args['dest'] == 'root@el6host:/tmp/deleteme'"
     - "self.task.become == True"
diff --git a/tests/unit/plugins/action/fixtures/synchronize/basic_become_cli/meta.yaml b/tests/unit/plugins/action/fixtures/synchronize/basic_become_cli/meta.yaml
index 5e558012a5..294bfdeb1b 100644
--- a/tests/unit/plugins/action/fixtures/synchronize/basic_become_cli/meta.yaml
+++ b/tests/unit/plugins/action/fixtures/synchronize/basic_become_cli/meta.yaml
@@ -25,7 +25,8 @@ asserts:
     - "self.execute_called"
     - "self.final_module_args['_local_rsync_path'] == 'rsync'"
     # this is a crucial aspect of this scenario ...
-    - "self.final_module_args['rsync_path'] == 'sudo rsync'"
+    # note: become_user None -> root
+    - "self.final_module_args['rsync_path'] == 'sudo -u root rsync'"
     - "self.final_module_args['src'] == '/tmp/deleteme'"
     - "self.final_module_args['dest'] == 'root@el6host:/tmp/deleteme'"
     - "self.task.become == None"