diff --git a/tensorflow/lite/kernels/fully_connected_test.cc b/tensorflow/lite/kernels/fully_connected_test.cc
index 7a69b999f1f..114d30ebf40 100644
--- a/tensorflow/lite/kernels/fully_connected_test.cc
+++ b/tensorflow/lite/kernels/fully_connected_test.cc
@@ -132,7 +132,6 @@ static float fully_connected_golden_output[] = {
 
 class BaseFullyConnectedOpModel : public SingleOpModel {
  public:
-  // TODO(ahentz): test different activation types too.
   BaseFullyConnectedOpModel(
       TfLiteRegistration* registration, int units, int batches,
       const TensorData& input, const TensorData& output = {TensorType_FLOAT32},
@@ -428,6 +427,99 @@ TEST(FloatFullyConnectedOpTest, SimpleTestNoBias) {
   EXPECT_THAT(m.GetOutput(), ElementsAre(10, 8));
 }
 
+TEST(FloatFullyConnectedOpTest, ActivationRelu6) {
+  // The optimized kernel assumes that the bias is specified.
+  FloatFullyConnectedOpModel m(
+      ops::builtin::Register_FULLY_CONNECTED_PIE(),
+      /*units=*/1, /*batches=*/2,
+      /*input=*/{TensorType_FLOAT32, {2, 2}},
+      /*output=*/{TensorType_FLOAT32},
+      /*bias_tensor_optional=*/false,
+      /*ActivationFunctionType*/ ActivationFunctionType_RELU6);
+  m.SetWeights({
+      2, 4,  // u = 0
+  });
+
+  m.SetInput({
+      1, 2,  // b = 0
+      2, 1,  // b = 1
+  });
+
+  m.Invoke();
+
+  EXPECT_THAT(m.GetOutput(), ElementsAre(6, 6));
+}
+
+TEST(FloatFullyConnectedOpTest, ActivationTanh) {
+  // The optimized kernel assumes that the bias is specified.
+  FloatFullyConnectedOpModel m(
+      ops::builtin::Register_FULLY_CONNECTED_PIE(),
+      /*units=*/1, /*batches=*/2,
+      /*input=*/{TensorType_FLOAT32, {2, 2}},
+      /*output=*/{TensorType_FLOAT32},
+      /*bias_tensor_optional=*/false,
+      /*ActivationFunctionType*/ ActivationFunctionType_TANH);
+  m.SetWeights({
+      -2, 1,  // u = 0
+  });
+
+  m.SetInput({
+      1, 4,  // b = 0
+      2, 1,  // b = 1
+  });
+
+  m.Invoke();
+
+  EXPECT_THAT(m.GetOutput(),
+              ElementsAreArray(ArrayFloatNear({0.964028, -0.995055})));
+}
+
+TEST(FloatFullyConnectedOpTest, ActivationSign) {
+  FloatFullyConnectedOpModel m(
+      ops::builtin::Register_FULLY_CONNECTED_GENERIC_OPT(),
+      /*units=*/1, /*batches=*/2,
+      /*input=*/{TensorType_FLOAT32, {2, 2}},
+      /*output=*/{TensorType_FLOAT32},
+      /*bias_tensor_optional=*/false,
+      /*ActivationFunctionType*/ ActivationFunctionType_SIGN_BIT);
+  m.SetWeights({
+      2, 4,  // u = 0
+  });
+  m.SetBias({1});
+
+  m.SetInput({
+      1, -2,  // b = 0
+      -2, 1,  // b = 1
+  });
+
+  m.Invoke();
+
+  EXPECT_THAT(m.GetOutput(), ElementsAre(-5, 1));
+}
+
+TEST(FloatFullyConnectedOpTest, ActivationN1) {
+  FloatFullyConnectedOpModel m(
+      ops::builtin::Register_FULLY_CONNECTED_GENERIC_OPT(),
+      /*units=*/1, /*batches=*/2,
+      /*input=*/{TensorType_FLOAT32, {2, 2}},
+      /*output=*/{TensorType_FLOAT32},
+      /*bias_tensor_optional=*/false,
+      /*ActivationFunctionType*/ ActivationFunctionType_RELU_N1_TO_1);
+  m.SetWeights({
+      2, 4,  // u = 0
+  });
+  m.SetBias({1});
+
+  m.SetInput({
+      1, -2,  // b = 0
+      -2, 1,  // b = 1
+  });
+
+  m.Invoke();
+
+  EXPECT_THAT(m.GetOutput(), ElementsAre(-1, 1));
+}
+
 TEST_P(QuantizedFullyConnectedOpTest, SimpleTestQuantizedUint8) {
   QuantizedFullyConnectedOpModel m(
       GetRegistration(), /*units=*/3, /*batches*/ 2,