diff --git a/moto/secretsmanager/models.py b/moto/secretsmanager/models.py
index 0aaa2027a..5542cb3e3 100644
--- a/moto/secretsmanager/models.py
+++ b/moto/secretsmanager/models.py
@@ -578,6 +578,20 @@ class SecretsManagerBackend(BaseBackend):
 
         return secret_id
 
+    def untag_resource(self, secret_id, tag_keys):
+
+        if secret_id not in self.secrets.keys():
+            raise SecretNotFoundException()
+
+        secret = self.secrets[secret_id]
+        tags = secret.tags
+
+        for tag in tags:
+            if tag["Key"] in tag_keys:
+                tags.remove(tag)
+
+        return secret_id
+
     @staticmethod
     def get_resource_policy(secret_id):
         resource_policy = {
diff --git a/moto/secretsmanager/responses.py b/moto/secretsmanager/responses.py
index e1c0517db..a469f5baa 100644
--- a/moto/secretsmanager/responses.py
+++ b/moto/secretsmanager/responses.py
@@ -162,3 +162,10 @@ class SecretsManagerResponse(BaseResponse):
         secret_id = self._get_param("SecretId")
         tags = self._get_param("Tags", if_none=[])
         return secretsmanager_backends[self.region].tag_resource(secret_id, tags)
+
+    def untag_resource(self):
+        secret_id = self._get_param("SecretId")
+        tag_keys = self._get_param("TagKeys", if_none=[])
+        return secretsmanager_backends[self.region].untag_resource(
+            secret_id=secret_id, tag_keys=tag_keys
+        )
diff --git a/tests/test_secretsmanager/test_secretsmanager.py b/tests/test_secretsmanager/test_secretsmanager.py
index 539b878f9..1e3515709 100644
--- a/tests/test_secretsmanager/test_secretsmanager.py
+++ b/tests/test_secretsmanager/test_secretsmanager.py
@@ -950,6 +950,35 @@ def test_tag_resource():
     )
 
 
+@mock_secretsmanager
+def test_untag_resource():
+    conn = boto3.client("secretsmanager", region_name="us-west-2")
+    conn.create_secret(Name="test-secret", SecretString="foosecret")
+    conn.tag_resource(
+        SecretId="test-secret",
+        Tags=[
+            {"Key": "FirstTag", "Value": "SomeValue"},
+            {"Key": "SecondTag", "Value": "SomeValue"},
+        ],
+    )
+
+    conn.untag_resource(SecretId="test-secret", TagKeys=["FirstTag"])
+    secrets = conn.list_secrets()
+    assert secrets["SecretList"][0].get("Tags") == [
+        {"Key": "SecondTag", "Value": "SomeValue"},
+    ]
+
+    with pytest.raises(ClientError) as cm:
+        conn.untag_resource(
+            SecretId="dummy-test-secret", TagKeys=["FirstTag"],
+        )
+
+    assert (
+        "Secrets Manager can't find the specified secret."
+        == cm.value.response["Error"]["Message"]
+    )
+
+
 @mock_secretsmanager
 def test_secret_versions_to_stages_attribute_discrepancy():
     client = boto3.client("secretsmanager", region_name="us-west-2")