diff --git a/ansible/README.md b/ansible/README.md
index 3dfc9de035..38d3bfb19d 100644
--- a/ansible/README.md
+++ b/ansible/README.md
@@ -137,7 +137,7 @@ There are a few configuration files that can be configured before execution of t
 
 ### Variables
 
-Most of the following variables are defined in `vars/all.yml`. `rhel_target_version` is provided by the `setup-microshift-host` role defaults and can be set in `vars/all.yml` or passed directly with `-e`.
+Most of the following variables are defined in `vars/all.yml`. The source-build variables and `rhel_target_version` are provided by role defaults and can be set in `vars/all.yml` or passed directly with `-e`.
 
 | Variable Name  | Description | Default |
 | -------------- | ----------- | ------- |
@@ -151,6 +151,9 @@ Most of the following variables are defined in `vars/all.yml`. `rhel_target_vers
 | `prometheus_logging` | Set up logging and exporters on the nodes | `true` |
 | `install_microshift` | Install MicroShift (from packages or source) | `false` |
 | `build_microshift` | Build MicroShift from source instead of installing packages | `false` |
+| `microshift_source_dir` | Existing MicroShift Git worktree on the managed host to build instead of updating the default checkout | `""` |
+| `microshift_git_revision` | Git revision to check out when building MicroShift from source | `"release-<major.minor>"` |
+| `microshift_git_refspec` | Additional Git refspec to fetch when building MicroShift from source (e.g. `+refs/pull/123/head:refs/remotes/origin/pr-123`) | `""` |
 | `build_etcd_binary` | Build and deploy a separate etcd process | `false` |
 | `microshift_version` | MicroShift version to install (supports EC/RC prereleases) | `"4.20"` |
 | `enable_gpu` | Install NVIDIA GPU drivers and container toolkit for GPU workloads | `false` |
@@ -158,6 +161,14 @@ Most of the following variables are defined in `vars/all.yml`. `rhel_target_vers
 | `run_workloads` | Run kube-burner performance workloads | `false` |
 | `rhel_target_version` | Pin RHEL to a specific version during upgrades (e.g., "9.8") | `undefined` |
 
+Source builds update the existing checkout in `microshift_dir` to `microshift_git_revision`. By default, the revision is the release branch derived from
+`microshift_version`; for example, both `4.21.0` and `latest-4.21` select `release-4.21`. Set it explicitly to build another branch, tag, or commit.
+A commit SHA may require `microshift_git_refspec` when the commit is not reachable from a branch or tag fetched by default. Checking out a SHA leaves the
+repository in detached HEAD state until a later branch-based run updates it.
+
+Set `microshift_source_dir` to build a complete Git worktree that is already present on the managed host. The caller is responsible for staging and
+updating the worktree, including its `.git` metadata. When set, the Git checkout task is skipped and the Git revision and refspec variables are ignored.
+
 ### Inventory Configuration
 
 The inventory configuration file is located at `inventory/inventory`.
diff --git a/ansible/roles/install-microshift/defaults/main.yml b/ansible/roles/install-microshift/defaults/main.yml
index 4c5e08bf0a..e0a337d20c 100644
--- a/ansible/roles/install-microshift/defaults/main.yml
+++ b/ansible/roles/install-microshift/defaults/main.yml
@@ -10,6 +10,16 @@ microshift_dir: "{{ ansible_facts.env.HOME }}/microshift"
 microshift_repo: https://github.com/openshift/microshift.git
 microshift_rpms: []
 microshift_version: 4.22.0
+# Optional existing MicroShift Git worktree to build instead of updating
+# microshift_dir from microshift_repo.
+microshift_source_dir: ""
+# Directory used by the source build tasks.
+microshift_build_dir: "{{ microshift_source_dir | default(microshift_dir, true) }}"
+# Git revision to check out when building MicroShift from source.
+microshift_git_revision: "release-{{ (microshift_version | regex_replace('^latest-', '')).split('.')[:2] | join('.') }}"
+# Optional additional Git refspec to fetch when building from source,
+# e.g. "+refs/pull/123/head:refs/remotes/origin/pr-123"
+microshift_git_refspec: ""
 
 du_dirs:
   - /
diff --git a/ansible/roles/install-microshift/tasks/main.yml b/ansible/roles/install-microshift/tasks/main.yml
index 7ff70a7799..eb2ac3cd0d 100644
--- a/ansible/roles/install-microshift/tasks/main.yml
+++ b/ansible/roles/install-microshift/tasks/main.yml
@@ -55,31 +55,27 @@
           - cri-tools
         state: present
 
-    - name: check if microshift dir exists
-      ansible.builtin.stat:
-        path: "{{ microshift_dir }}"
-      register: ms_dir
-
-    - name: clone microshift git repo
+    - name: ensure microshift git checkout
       ansible.builtin.git:
         repo: "{{ microshift_repo }}"
         dest: "{{ microshift_dir }}"
-        version: "{{ microshift_version }}"
-      when: not ms_dir.stat.exists
+        version: "{{ microshift_git_revision }}"
+        refspec: "{{ microshift_git_refspec | default(omit, true) }}"
+      when: not microshift_source_dir
 
     - name: make clean
       ansible.builtin.command: make clean
       args:
-        chdir: "{{ microshift_dir }}"
+        chdir: "{{ microshift_build_dir }}"
 
     - name: make rpm
       ansible.builtin.command: make rpm
       args:
-        chdir: "{{ microshift_dir }}"
+        chdir: "{{ microshift_build_dir }}"
 
     - name: find built RPMs
       ansible.builtin.find:
-        paths: "{{ microshift_dir }}"
+        paths: "{{ microshift_build_dir }}"
         patterns: '*.rpm'
         recurse: yes
       register: microshift_find