diff --git a/collectoss/application/cli/db.py b/collectoss/application/cli/db.py
index 7b6bc7c09..599dac517 100644
--- a/collectoss/application/cli/db.py
+++ b/collectoss/application/cli/db.py
@@ -21,6 +21,7 @@
 )
 
 from collectoss.application.db.session import DatabaseSession
+from collectoss.application.db.lib import merge_contributors
 from sqlalchemy import update
 from datetime import datetime
 from collectoss.application.db.models import Repo
@@ -151,6 +152,29 @@ def get_repo_groups(ctx: click.Context) -> pd.DataFrame:
     return df
 
 
+@cli.command("merge-contributors")
+@click.argument("primary_cntrb_id")
+@click.argument("duplicate_cntrb_id")
+@test_connection
+@test_db_connection
+@with_database
+@click.pass_context
+def merge_contributors_cmd(ctx: click.Context, primary_cntrb_id: str, duplicate_cntrb_id: str) -> None:
+    """Merge a duplicate contributor into the primary contributor."""
+    try:
+        merge_contributors(
+            ctx.obj.engine,
+            primary_cntrb_id,
+            duplicate_cntrb_id,
+        )
+        click.echo(
+            f"Merged duplicate contributor {duplicate_cntrb_id} into primary contributor {primary_cntrb_id}"
+        )
+    except Exception as e:
+        logger.error(f"Failed to merge contributors: {e}")
+        raise
+
+
 @cli.command("add-repo-groups")
 @click.argument("filename", type=click.Path(exists=True))
 @test_connection
diff --git a/collectoss/application/db/lib.py b/collectoss/application/db/lib.py
index c5394365d..3f7f5303a 100644
--- a/collectoss/application/db/lib.py
+++ b/collectoss/application/db/lib.py
@@ -92,6 +92,108 @@ def fetchall_data_from_sql_text(sql_text):
         result = connection.execute(sql_text)
     return [dict(row) for row in result.mappings()]
 
+
+def merge_contributors(engine, primary_cntrb_id: str, duplicate_cntrb_id: str) -> None:
+    """Merge a duplicate contributor record into a primary contributor record.
+
+    This updates all foreign-key references to the duplicate contributor id
+    to use the primary contributor id, merges contributor alias rows,
+    and deletes the duplicate contributor row.
+    """
+
+    if primary_cntrb_id == duplicate_cntrb_id:
+        raise ValueError("Primary and duplicate contributor IDs must differ")
+
+    with engine.begin() as connection:
+        primary_exists = connection.execute(
+            s.sql.text(
+                "SELECT 1 FROM data.contributors WHERE cntrb_id = :id"
+            ),
+            {"id": primary_cntrb_id},
+        ).scalar()
+
+        duplicate_exists = connection.execute(
+            s.sql.text(
+                "SELECT 1 FROM data.contributors WHERE cntrb_id = :id"
+            ),
+            {"id": duplicate_cntrb_id},
+        ).scalar()
+
+        if not primary_exists:
+            raise ValueError(f"Primary contributor not found: {primary_cntrb_id}")
+        if not duplicate_exists:
+            raise ValueError(f"Duplicate contributor not found: {duplicate_cntrb_id}")
+
+        connection.execute(
+            s.sql.text(
+                """
+                DELETE FROM data.contributors_aliases
+                WHERE cntrb_id = :duplicate_id
+                  AND alias_email IN (
+                    SELECT alias_email
+                    FROM data.contributors_aliases
+                    WHERE cntrb_id = :primary_id
+                  )
+                """
+            ),
+            {"duplicate_id": duplicate_cntrb_id, "primary_id": primary_cntrb_id},
+        )
+
+        connection.execute(
+            s.sql.text(
+                """
+                UPDATE data.contributors_aliases
+                SET cntrb_id = :primary_id
+                WHERE cntrb_id = :duplicate_id
+                """
+            ),
+            {"duplicate_id": duplicate_cntrb_id, "primary_id": primary_cntrb_id},
+        )
+
+        referencing_fks = connection.execute(
+            s.sql.text(
+                """
+                SELECT kcu.table_schema, kcu.table_name, kcu.column_name
+                FROM information_schema.table_constraints tc
+                JOIN information_schema.key_column_usage kcu
+                  ON tc.constraint_name = kcu.constraint_name
+                 AND tc.table_schema = kcu.table_schema
+                JOIN information_schema.constraint_column_usage ccu
+                  ON ccu.constraint_name = tc.constraint_name
+                 AND ccu.table_schema = tc.table_schema
+                WHERE tc.constraint_type = 'FOREIGN KEY'
+                  AND ccu.table_schema = 'data'
+                  AND ccu.table_name = 'contributors'
+                  AND ccu.column_name = 'cntrb_id'
+                """
+            )
+        ).mappings()
+
+        for fk in referencing_fks:
+            table_schema = fk["table_schema"]
+            table_name = fk["table_name"]
+            column_name = fk["column_name"]
+
+            if table_schema == "data" and table_name == "contributors_aliases":
+                continue
+
+            table_ref = f'"{table_schema}"."{table_name}"'
+            sql = s.sql.text(
+                f"UPDATE {table_ref} SET \"{column_name}\" = :primary_id WHERE \"{column_name}\" = :duplicate_id"
+            )
+            connection.execute(
+                sql,
+                {"primary_id": primary_cntrb_id, "duplicate_id": duplicate_cntrb_id},
+            )
+
+        connection.execute(
+            s.sql.text(
+                "DELETE FROM data.contributors WHERE cntrb_id = :duplicate_id"
+            ),
+            {"duplicate_id": duplicate_cntrb_id},
+        )
+
+
 def get_repo_by_repo_git(repo_git: str):
 
     with get_session() as session: