diff --git a/litellm/llms/anthropic/wif.py b/litellm/llms/anthropic/wif.py
index adfd16c1e74..b096a11ace4 100644
--- a/litellm/llms/anthropic/wif.py
+++ b/litellm/llms/anthropic/wif.py
@@ -175,7 +175,7 @@ def _resolve_identity_source(
         legacy_ref: Final = _resolve_assertion_ref(litellm_params)
         return (legacy_ref, None) if legacy_ref is not None else None
     params: Final[Mapping[str, object]] = MappingProxyType(
-        {key: value for key, value in (litellm_params or _EMPTY_PARAMS).items() if value is not None}
+        {key: value for key, value in (litellm_params or _EMPTY_PARAMS).items() if _is_set(value)}
     )
     match source_kind:
         case AnthropicIdentitySourceKind.internal_issuer.value:
@@ -263,7 +263,7 @@ def _build_variant(
     field_map: Mapping[str, str],
 ) -> _IdentitySourceVariant:
     fields: Final = MappingProxyType(
-        {field_map[key]: value for key, value in litellm_params.items() if key in field_map}
+        {field_map[key]: value for key, value in litellm_params.items() if key in field_map and _is_set(value)}
     )
     try:
         return model.model_validate(fields)
@@ -512,6 +512,10 @@ def _config_value(litellm_params: Mapping[str, object] | None, param_key: str, e
     return _param_str(litellm_params, param_key) or _env_str(env_name)
 
 
+def _is_set(value: object) -> bool:
+    return value is not None and value != ""
+
+
 def _param_str(litellm_params: Mapping[str, object] | None, key: str) -> str | None:
     if litellm_params is None:
         return None
diff --git a/tests/unit/llms/anthropic/test_anthropic_wif.py b/tests/unit/llms/anthropic/test_anthropic_wif.py
index a66daae48da..a054b4d130c 100644
--- a/tests/unit/llms/anthropic/test_anthropic_wif.py
+++ b/tests/unit/llms/anthropic/test_anthropic_wif.py
@@ -25,7 +25,6 @@ from litellm.llms.base_llm.auth.identity_source import (
 )
 from litellm.llms.base_llm.auth.jwt_signing import build_jwks, rfc7638_thumbprint
 from litellm.llms.base_llm.auth.token_exchange import JwtBearerTokenExchangeEngine
-from litellm.types.router import GenericLiteLLMParams
 from litellm.llms.base_llm.auth.types import (
     AssertionSourceError,
     ExchangeError,
@@ -34,6 +33,7 @@ from litellm.llms.base_llm.auth.types import (
     TokenEndpointError,
     TokenTransportError,
 )
+from litellm.types.router import GenericLiteLLMParams
 
 WIF_ENV_VARS: Final = (
     "ANTHROPIC_FEDERATION_RULE_ID",
@@ -1132,6 +1132,28 @@ class TestIdentitySourceValidationFailsClosed:
                 }
             )
 
+    def test_blank_optional_and_foreign_fields_count_as_unset(self):
+        configured = {
+            "anthropic_federation_rule_id": "fdrl_1",
+            "anthropic_organization_id": "org-1",
+            "anthropic_identity_source": "internal_issuer",
+            "anthropic_issuer_url": "https://issuer.internal.example",
+            "anthropic_issuer_subject": "workload-a",
+            "anthropic_issuer_signing_key_ref": ISSUER_SIGNING_KEY_REF,
+        }
+        with_blanks = {
+            **configured,
+            "anthropic_issuer_audience": "",
+            "anthropic_issuer_ttl_seconds": "",
+            "anthropic_keycloak_client_id": "",
+        }
+
+        expected = resolve_anthropic_wif_params(configured)
+        actual = resolve_anthropic_wif_params(with_blanks)
+
+        assert expected is not None and actual is not None
+        assert actual.assertion_ref == expected.assertion_ref
+
     def test_secret_pasted_into_wrong_field_never_appears_in_the_error(self):
         secret_value = "super-secret-client-value-xyz"
         with pytest.raises(litellm.AuthenticationError) as exc_info:
diff --git a/tests/unit/proxy/credential_endpoints/test_endpoints.py b/tests/unit/proxy/credential_endpoints/test_endpoints.py
index b27cc0e417a..7d667f72502 100644
--- a/tests/unit/proxy/credential_endpoints/test_endpoints.py
+++ b/tests/unit/proxy/credential_endpoints/test_endpoints.py
@@ -439,6 +439,32 @@ class TestCredentialJwksExport:
         assert "JWKS_TEST_SIGNING_KEY" not in response.text
         assert "PRIVATE KEY" not in response.text
 
+    def test_jwks_export_treats_blank_optional_fields_as_unset(self, restore_credential_list, monkeypatch):
+        monkeypatch.setenv("JWKS_TEST_SIGNING_KEY", _generate_es256_pem())
+        monkeypatch.setattr(
+            litellm,
+            "credential_list",
+            [
+                CredentialItem(
+                    credential_name="anthropic-issuer-blanks",
+                    credential_values={
+                        "anthropic_identity_source": "internal_issuer",
+                        "anthropic_issuer_url": "https://issuer.example.com",
+                        "anthropic_issuer_subject": "my-workload",
+                        "anthropic_issuer_signing_key_ref": "os.environ/JWKS_TEST_SIGNING_KEY",
+                        "anthropic_issuer_audience": "",
+                        "anthropic_issuer_ttl_seconds": "",
+                    },
+                    credential_info={"custom_llm_provider": "anthropic"},
+                )
+            ],
+        )
+
+        response = _get_jwks("anthropic-issuer-blanks")
+
+        assert response.status_code == 200, response.text
+        assert response.json()["keys"][0]["kty"] == "EC"
+
     def test_jwks_export_accepts_the_dashboard_provider_casing(self, restore_credential_list, monkeypatch):
         monkeypatch.setenv("JWKS_TEST_SIGNING_KEY", _generate_es256_pem())
         monkeypatch.setattr(