diff --git a/changelogs/fragments/11689-composer-create-project-idempotent.yml b/changelogs/fragments/11689-composer-create-project-idempotent.yml
new file mode 100644
index 0000000000..6235e3e878
--- /dev/null
+++ b/changelogs/fragments/11689-composer-create-project-idempotent.yml
@@ -0,0 +1,6 @@
+minor_changes:
+  - composer - add ``force`` parameter; when ``command=create-project``, the module now checks
+    whether a ``composer.json`` already exists in ``working_dir`` and skips the command if so,
+    making the task idempotent. Set ``force=true`` to always run the command regardless
+    (https://github.com/ansible-collections/community.general/issues/725,
+    https://github.com/ansible-collections/community.general/pull/11689).
diff --git a/plugins/modules/composer.py b/plugins/modules/composer.py
index c649aae37f..731cfa1250 100644
--- a/plugins/modules/composer.py
+++ b/plugins/modules/composer.py
@@ -98,6 +98,14 @@ options:
         these.
     default: false
     type: bool
+  force:
+    description:
+      - When O(command) is V(create-project), the module checks whether a V(composer.json) already
+        exists in O(working_dir) and skips the command if it does, making the task idempotent.
+      - Set to V(true) to always run the command regardless.
+    default: false
+    type: bool
+    version_added: 12.6.0
   composer_executable:
     type: path
     description:
@@ -139,6 +147,7 @@ EXAMPLES = r"""
     arguments: my/package
 """
 
+import os
 import re
 import shlex
 
@@ -212,6 +221,7 @@ def main():
             optimize_autoloader=dict(default=True, type="bool"),
             classmap_authoritative=dict(default=False, type="bool"),
             ignore_platform_reqs=dict(default=False, type="bool"),
+            force=dict(default=False, type="bool"),
             composer_executable=dict(type="path"),
         ),
         required_if=[("global_command", False, ["working_dir"])],
@@ -257,6 +267,12 @@ def main():
             option = f"--{option}"
             options.append(option)
 
+    working_dir = module.params["working_dir"]
+
+    if command == "create-project" and not module.params["force"]:
+        if working_dir and os.path.exists(os.path.join(working_dir, "composer.json")):
+            module.exit_json(changed=False, msg="composer.json already exists in working_dir, skipping create-project")
+
     if module.check_mode:
         if "dry-run" in available_options:
             options.append("--dry-run")
diff --git a/tests/unit/plugins/modules/test_composer.py b/tests/unit/plugins/modules/test_composer.py
index 71648bfa86..b0ea50a47d 100644
--- a/tests/unit/plugins/modules/test_composer.py
+++ b/tests/unit/plugins/modules/test_composer.py
@@ -9,6 +9,17 @@ from __future__ import annotations
 
 from ansible_collections.community.general.plugins.modules import composer
 
-from .uthelper import RunCommandMock, UTHelper
+from .uthelper import RunCommandMock, TestCaseMock, UTHelper
 
-UTHelper.from_module(composer, __name__, mocks=[RunCommandMock])
+
+class OsPathExistsMock(TestCaseMock):
+    name = "os_path_exists"
+
+    def setup(self, mocker):
+        mocker.patch("os.path.exists", return_value=self.mock_specs.get("return_value", False))
+
+    def check(self, test_case, results):
+        pass
+
+
+UTHelper.from_module(composer, __name__, mocks=[RunCommandMock, OsPathExistsMock])
diff --git a/tests/unit/plugins/modules/test_composer.yaml b/tests/unit/plugins/modules/test_composer.yaml
index 545e9d0176..323f1b2516 100644
--- a/tests/unit/plugins/modules/test_composer.yaml
+++ b/tests/unit/plugins/modules/test_composer.yaml
@@ -3,6 +3,25 @@
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 ---
+anchors:
+  help_install: &help_install
+    command: ["/testbin/php", "/testbin/composer", "help", "install", "--working-dir", "/var/www/foo", "--no-interaction", "--format=json"]
+    rc: 0
+    out: |
+      {"definition": {"options": ["a", "b", "c"]}}
+    err: ''
+  help_create_project: &help_create_project
+    command: ["/testbin/php", "/testbin/composer", "help", "create-project", "--working-dir", "/var/www/foo", "--no-interaction", "--format=json"]
+    rc: 0
+    out: |
+      {"definition": {"options": ["a", "b", "c"]}}
+    err: ''
+  run_create_project: &run_create_project
+    command: ["/testbin/php", "/testbin/composer", "create-project", "--working-dir", "/var/www/foo", "vendor/package"]
+    rc: 0
+    out: ''
+    err: ''
+
 test_cases:
   - id: composer
     input:
@@ -12,12 +31,50 @@ test_cases:
       changed: true
     mocks:
       run_command:
-        - command: ["/testbin/php", "/testbin/composer", "help", "install", "--working-dir", "/var/www/foo", "--no-interaction", "--format=json"]
-          rc: 0
-          out: |
-            {"definition": {"options": ["a", "b", "c"]}}
-          err: ''
+        - *help_install
         - command: ["/testbin/php", "/testbin/composer", "install", "--working-dir", "/var/www/foo"]
           rc: 0
           out: ''
           err: ''
+
+  - id: create_project_runs
+    input:
+      command: create-project
+      arguments: "vendor/package"
+      working_dir: "/var/www/foo"
+    output:
+      changed: true
+    mocks:
+      os_path_exists:
+        return_value: false
+      run_command:
+        - *help_create_project
+        - *run_create_project
+
+  - id: create_project_skips_when_exists
+    input:
+      command: create-project
+      arguments: "vendor/package"
+      working_dir: "/var/www/foo"
+    output:
+      changed: false
+    mocks:
+      os_path_exists:
+        return_value: true
+      run_command:
+        - *help_create_project
+
+  - id: create_project_force
+    input:
+      command: create-project
+      arguments: "vendor/package"
+      working_dir: "/var/www/foo"
+      force: true
+    output:
+      changed: true
+    mocks:
+      os_path_exists:
+        return_value: true
+      run_command:
+        - *help_create_project
+        - *run_create_project