diff --git a/.github/workflows/cleanup.yaml b/.github/workflows/cleanup.yaml
index d0aad80..1d90a77 100644
--- a/.github/workflows/cleanup.yaml
+++ b/.github/workflows/cleanup.yaml
@@ -34,4 +34,5 @@ jobs:
           last_commit_age_days: 0
           dry_run: yes
           ignore_branches: test_prefix/one,test_prefix/two,test_prefix_ignored/one
-          branch_limit: 1
+          branch_limit: 10
+          only_closed_prs: yes
diff --git a/action.yml b/action.yml
index c4e514a..e7175c0 100644
--- a/action.yml
+++ b/action.yml
@@ -34,6 +34,10 @@ inputs:
     description: "The max number of branches that can be deleted"
     required: false
     default: "100"
+  only_closed_prs:
+    description: "Whether we're only deleting branches that belong to closed PRs. Defaults to 'no'. Possible values: yes, no (case sensitive)"
+    required: false
+    default: "no"
 
 outputs:
   deleted_branches: # id of output
@@ -54,5 +58,6 @@ runs:
         python3 main.py --ignore-branches=${{ inputs.ignore_branches }} \
           --last-commit-age-days=${{ inputs.last_commit_age_days }} --allowed-prefixes=${{ inputs.allowed_prefixes }} \
           --dry-run=${{ inputs.dry_run }} --github-token=${{ inputs.github_token }} \
-          --github-base-url=${{ inputs.github_base_url }} --branch-limit=${{ inputs.branch_limit }}
+          --github-base-url=${{ inputs.github_base_url }} --branch-limit=${{ inputs.branch_limit }} \
+          --only-closed-prs=${{ inputs.only_closed_prs }}
       shell: bash
diff --git a/src/actions.py b/src/actions.py
index 0967cbe..4062da2 100644
--- a/src/actions.py
+++ b/src/actions.py
@@ -11,7 +11,8 @@ def run_action(options: Options) -> list:
         last_commit_age_days=options.last_commit_age_days,
         ignore_branches=options.ignore_branches,
         allowed_prefixes=options.allowed_prefixes,
-        branch_limit=options.branch_limit
+        branch_limit=options.branch_limit,
+        only_closed_prs=options.only_closed_prs,
     )
 
     print(f"Branches queued for deletion: {branches}")
diff --git a/src/github.py b/src/github.py
index 5ade934..d985e7b 100644
--- a/src/github.py
+++ b/src/github.py
@@ -23,7 +23,8 @@ def get_deletable_branches(
             last_commit_age_days: int,
             ignore_branches: list[str],
             allowed_prefixes: list[str],
-            branch_limit: int
+            branch_limit: int,
+            only_closed_prs: bool,
     ) -> list[str]:
         if branch_limit < 1:
             return []
@@ -76,6 +77,11 @@ def get_deletable_branches(
                     if found_prefix is False:
                         print(f'Ignoring `{branch_name}` because it does not match any provided allowed_prefixes')
                         continue
+                
+                # If only_closed_prs is True, move on if branch is not base for a closed pull request
+                if only_closed_prs is True and self.is_closed_pull_request_base(branch=branch_name) is False:
+                    print(f'Ignoring `{branch_name}` because only_closed_prs is True and it is not base for a closed pull request')
+                    continue
 
                 # Move on if commit is in an open pull request
                 if self.has_open_pulls(commit_hash=commit_hash):
@@ -152,6 +158,20 @@ def has_open_pulls(self, commit_hash: str) -> bool:
 
         return False
 
+    def is_closed_pull_request_base(self, branch: str) -> bool:
+        """
+        Returns true if the given branch is base for a closed pull request.
+        """
+        url = f'{self.base_url}/repos/{self.repo}/pulls?base={branch}&state=closed'
+        headers = self.make_headers()
+        headers['accept'] = 'application/vnd.github.groot-preview+json'
+
+        response = requests.get(url=url, headers=headers)
+        if response.status_code != 200:
+            raise RuntimeError(f'Failed to make request to {url}. {response} {response.json()}')
+
+        return len(response.json()) > 0
+
     def is_pull_request_base(self, branch: str) -> bool:
         """
         Returns true if the given branch is base for another pull request.
diff --git a/src/io.py b/src/io.py
index 3c3977e..89b1d6f 100644
--- a/src/io.py
+++ b/src/io.py
@@ -15,6 +15,7 @@ def __init__(
             branch_limit: int,
             dry_run: bool = True,
             github_base_url: str = DEFAULT_GITHUB_API_URL,
+            only_closed_prs: bool = False,
     ):
         self.ignore_branches = ignore_branches
         self.last_commit_age_days = last_commit_age_days
@@ -24,6 +25,7 @@ def __init__(
         self.dry_run = dry_run
         self.github_base_url = github_base_url
         self.branch_limit = branch_limit
+        self.only_closed_prs = only_closed_prs
 
 
 class InputParser:
@@ -67,6 +69,13 @@ def get_args() -> argparse.Namespace:
             type=int,
         )
 
+        parser.add_argument(
+            "--only-closed-prs",
+            choices=["yes", "no"],
+            default="no",
+            help="Whether we're only deleting branches that belong to closed PRs. Defaults to 'no'. Possible values: yes, no (case sensitive)"
+        )
+
         return parser.parse_args()
 
     def parse_input(self) -> Options:
@@ -84,6 +93,7 @@ def parse_input(self) -> Options:
 
         # Dry run can only be either `true` or `false`, as strings due to github actions input limitations
         dry_run = False if args.dry_run == 'no' else True
+        only_closed_prs = False if args.only_closed_prs == 'no' else True
 
         return Options(
             ignore_branches=ignore_branches,
@@ -93,7 +103,8 @@ def parse_input(self) -> Options:
             github_token=args.github_token,
             github_repo=getenv('GITHUB_REPOSITORY'),
             github_base_url=args.github_base_url,
-            branch_limit=args.branch_limit
+            branch_limit=args.branch_limit,
+            only_closed_prs=only_closed_prs,
         )