diff --git a/Modules/Filtering/LabelMap/ITKKWStyleOverwrite.txt b/Modules/Filtering/LabelMap/ITKKWStyleOverwrite.txt
index 833fbdf5696..3ea0f336e71 100644
--- a/Modules/Filtering/LabelMap/ITKKWStyleOverwrite.txt
+++ b/Modules/Filtering/LabelMap/ITKKWStyleOverwrite.txt
@@ -2,4 +2,5 @@ test/*\.cxx Namespace Disable
 test/itkAttributePositionLabelMapFilterTest1.cxx Namespace Disable
 test/itkShapeLabelMapFilterGTest.cxx Namespace Disable
 test/itkStatisticsLabelMapFilterGTest.cxx Namespace Disable
+test/itkUniqueLabelMapFiltersGTest.cxx Namespace Disable
 test/itkShapeLabelObjectAccessorsTest1.cxx SemicolonSpace Disable
diff --git a/Modules/Filtering/LabelMap/test/CMakeLists.txt b/Modules/Filtering/LabelMap/test/CMakeLists.txt
index 32008f30ebc..0e15f959ea8 100644
--- a/Modules/Filtering/LabelMap/test/CMakeLists.txt
+++ b/Modules/Filtering/LabelMap/test/CMakeLists.txt
@@ -1592,6 +1592,8 @@ itk_add_test(
   1
   100)
 
-set(ITKLabelMapGTests itkShapeLabelMapFilterGTest.cxx itkStatisticsLabelMapFilterGTest.cxx)
+set(ITKLabelMapGTests itkShapeLabelMapFilterGTest.cxx
+        itkStatisticsLabelMapFilterGTest.cxx
+        itkUniqueLabelMapFiltersGTest.cxx)
 
 creategoogletestdriver(ITKLabelMap "${ITKLabelMap-Test_LIBRARIES}" "${ITKLabelMapGTests}")
diff --git a/Modules/Filtering/LabelMap/test/itkUniqueLabelMapFiltersGTest.cxx b/Modules/Filtering/LabelMap/test/itkUniqueLabelMapFiltersGTest.cxx
new file mode 100644
index 00000000000..ae1c3957cfb
--- /dev/null
+++ b/Modules/Filtering/LabelMap/test/itkUniqueLabelMapFiltersGTest.cxx
@@ -0,0 +1,309 @@
+/*=========================================================================
+ *
+ *  Copyright NumFOCUS
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *         https://www.apache.org/licenses/LICENSE-2.0.txt
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *=========================================================================*/
+
+#include "itkGTest.h"
+
+#include "itkImage.h"
+#include "itkLabelImageToStatisticsLabelMapFilter.h"
+#include "itkImageFileWriter.h"
+#include <algorithm>
+
+
+#include "itkLabelImageToLabelMapFilter.h"
+#include "itkObjectByObjectLabelMapFilter.h"
+#include "itkShapeLabelObjectAccessors.h"
+#include "itkFlatStructuringElement.h"
+#include "itkBinaryDilateImageFilter.h"
+#include "itkLabelUniqueLabelMapFilter.h"
+#include "itkTestingHashImageFilter.h"
+#include "itksys/SystemTools.hxx"
+#include "itkTestDriverIncludeRequiredFactories.h"
+
+
+namespace
+{
+
+class UniqueLabelMapFixture : public ::testing::Test
+{
+public:
+  UniqueLabelMapFixture() = default;
+  ~UniqueLabelMapFixture() override = default;
+
+protected:
+  void
+  SetUp() override
+  {
+    RegisterRequiredFactories();
+  }
+  void
+  TearDown() override
+  {}
+
+  std::string
+  GetTestName() const
+  {
+    return ::testing::UnitTest::GetInstance()->current_test_info()->name();
+  }
+
+  template <unsigned int D, typename TPixelType = unsigned short>
+  struct FixtureUtilities
+  {
+    static const unsigned int Dimension = D;
+
+    using LabelPixelType = TPixelType;
+    using LabelImageType = itk::Image<LabelPixelType, Dimension>;
+    using IndexType = typename LabelImageType::IndexType;
+
+    using LabelObjectType = itk::StatisticsLabelObject<LabelPixelType, Dimension>;
+
+    using LabelMapType = itk::LabelMap<itk::LabelObject<LabelPixelType, Dimension>>;
+
+
+    static typename LabelImageType::Pointer
+    CreateLabelImage(const std::vector<IndexType> & indices)
+    {
+      const size_t size = 25;
+      auto         image = LabelImageType::New();
+
+      typename LabelImageType::SizeType imageSize;
+      imageSize.Fill(size);
+      image->SetRegions(typename LabelImageType::RegionType(imageSize));
+      image->Allocate();
+      image->FillBuffer(0);
+
+      for (LabelPixelType id = 0; id < indices.size(); ++id)
+      {
+        image->SetPixel(indices[id], id + 1);
+      }
+      return image;
+    }
+
+    static typename LabelMapType::Pointer
+    LabelMapFromLabelImage(const LabelImageType * image, unsigned int dilateRadius = 0)
+    {
+      using ToLabelMapType = itk::LabelImageToLabelMapFilter<LabelImageType>;
+      auto toLabelMap = ToLabelMapType::New();
+      toLabelMap->SetInput(image);
+
+      if (dilateRadius == 0)
+      {
+        toLabelMap->Update();
+        return toLabelMap->GetOutput();
+      }
+
+      using KernelType = itk::FlatStructuringElement<Dimension>;
+      using DilateType = itk::BinaryDilateImageFilter<LabelImageType, LabelImageType, KernelType>;
+      auto                          dilate = DilateType::New();
+      typename KernelType::SizeType rad;
+      rad.Fill(dilateRadius);
+      dilate->SetKernel(KernelType::Ball(rad));
+
+
+      using OIType = itk::ObjectByObjectLabelMapFilter<LabelMapType, LabelMapType, DilateType>;
+      auto oi = OIType::New();
+      oi->SetInput(toLabelMap->GetOutput());
+      oi->SetFilter(dilate);
+      oi->SetPadSize(rad);
+
+      oi->Update();
+
+      return oi->GetOutput();
+    }
+  };
+
+  template <typename TLabelMap>
+  static typename itk::Image<typename TLabelMap::LabelObjectType::LabelType, TLabelMap::ImageDimension>::Pointer
+  LabelMapToLabelImage(TLabelMap * labelMap)
+  {
+    using ImageType = itk::Image<typename TLabelMap::LabelObjectType::LabelType, TLabelMap::ImageDimension>;
+    using L2IType = itk::LabelMapToLabelImageFilter<TLabelMap, ImageType>;
+    auto l2i = L2IType::New();
+    l2i->SetInput(labelMap);
+    l2i->Update();
+    return l2i->GetOutput();
+  }
+
+
+  template <typename TLabelMap>
+  void
+  CheckLabelMapOverlap(TLabelMap * labelMap)
+  {
+    for (auto & labelObject : labelMap->GetLabelObjects())
+    {
+      // Manually check each label object against all other label objects, to ensure that no two label objects share an
+      // index.
+      for (itk::SizeValueType lineNumber = 0; lineNumber < labelObject->GetNumberOfLines(); ++lineNumber)
+      {
+        auto line = labelObject->GetLine(lineNumber);
+        auto idx = line.GetIndex();
+        ASSERT_LE(line.GetLength(), labelObject->Size());
+        for (itk::SizeValueType lengthIndex = 0; lengthIndex < line.GetLength(); ++lengthIndex)
+        {
+          for (auto & checkObject : labelMap->GetLabelObjects())
+          {
+            if (checkObject != labelObject)
+            {
+              EXPECT_FALSE(checkObject->HasIndex(idx))
+                << "Label: " << int(labelObject->GetLabel()) << " and " << int(checkObject->GetLabel()) << " has index "
+                << idx << std::endl;
+            }
+          }
+          ++idx[0];
+        }
+      }
+    }
+  }
+
+  template <typename TImageType>
+  static std::string
+  MD5Hash(const TImageType * image)
+  {
+
+    using HashFilter = itk::Testing::HashImageFilter<TImageType>;
+    auto hasher = HashFilter::New();
+    hasher->SetInput(image);
+    hasher->InPlaceOff();
+    hasher->Update();
+    return hasher->GetHash();
+  }
+};
+} // namespace
+
+
+TEST_F(UniqueLabelMapFixture, EmptyImage)
+{
+  const std::vector<typename FixtureUtilities<2>::IndexType> indices = {};
+  auto                                                       image = FixtureUtilities<2>::CreateLabelImage(indices);
+  auto labelMap = FixtureUtilities<2>::LabelMapFromLabelImage(image.GetPointer(), 15);
+
+  auto filter = itk::LabelUniqueLabelMapFilter<typename decltype(labelMap)::ObjectType>::New();
+  filter->SetInput(labelMap);
+
+  CheckLabelMapOverlap(filter->GetOutput());
+  filter->Update();
+
+  auto out = LabelMapToLabelImage(filter->GetOutput());
+
+  // check the hash of out, should be all zeros
+  EXPECT_EQ(MD5Hash(out.GetPointer()), "393017b9101a884b66d64849d99a7d05");
+}
+
+
+TEST_F(UniqueLabelMapFixture, OneLabel)
+{
+  const std::vector<typename FixtureUtilities<2>::IndexType> indices = { { 10, 10 } };
+  auto                                                       image = FixtureUtilities<2>::CreateLabelImage(indices);
+  auto labelMap = FixtureUtilities<2>::LabelMapFromLabelImage(image.GetPointer(), 0);
+
+  auto filter = itk::LabelUniqueLabelMapFilter<typename decltype(labelMap)::ObjectType>::New();
+  filter->SetInput(labelMap);
+  filter->Update();
+
+  CheckLabelMapOverlap(filter->GetOutput());
+
+  auto out = LabelMapToLabelImage(filter->GetOutput());
+
+  EXPECT_EQ(MD5Hash(out.GetPointer()), MD5Hash(image.GetPointer()));
+  EXPECT_EQ(MD5Hash(out.GetPointer()), "9c8ee8f2fe887fd6d2393d6416df3fb6");
+}
+
+
+TEST_F(UniqueLabelMapFixture, OnesLabel)
+{
+  const std::vector<typename FixtureUtilities<2>::IndexType> indices = { { 0, 0 }, { 1, 0 }, { 2, 0 }, { 3, 0 },
+                                                                         { 0, 4 }, { 2, 4 }, { 0, 5 } };
+  auto                                                       image = FixtureUtilities<2>::CreateLabelImage(indices);
+  auto labelMap = FixtureUtilities<2>::LabelMapFromLabelImage(image.GetPointer(), 0);
+
+  auto filter = itk::LabelUniqueLabelMapFilter<typename decltype(labelMap)::ObjectType>::New();
+  filter->SetInput(labelMap);
+  filter->Update();
+
+  CheckLabelMapOverlap(filter->GetOutput());
+
+  auto out = LabelMapToLabelImage(filter->GetOutput());
+
+  EXPECT_EQ(MD5Hash(out.GetPointer()), MD5Hash(image.GetPointer()));
+  EXPECT_EQ(MD5Hash(out.GetPointer()), "220048b56395d98a8f20a5b1733bdde6");
+}
+
+
+TEST_F(UniqueLabelMapFixture, Dilate1)
+{
+  const std::vector<typename FixtureUtilities<2>::IndexType> indices = { { 0, 0 }, { 1, 0 }, { 2, 0 }, { 3, 0 },
+                                                                         { 0, 4 }, { 2, 4 }, { 0, 10 } };
+  auto                                                       image = FixtureUtilities<2>::CreateLabelImage(indices);
+  auto labelMap = FixtureUtilities<2>::LabelMapFromLabelImage(image.GetPointer(), 1);
+
+  auto filter = itk::LabelUniqueLabelMapFilter<typename decltype(labelMap)::ObjectType>::New();
+  filter->SetInput(labelMap);
+  filter->InPlaceOff();
+  filter->ReverseOrderingOff();
+  filter->Update();
+
+  CheckLabelMapOverlap(filter->GetOutput());
+
+  auto out = LabelMapToLabelImage(filter->GetOutput());
+
+  EXPECT_EQ(MD5Hash(out.GetPointer()), "8bfc8570ee203fa68be18fe055cf389d");
+  itk::WriteImage(out.GetPointer(), GetTestName() + "_off.png");
+
+  filter->ReverseOrderingOn();
+  filter->Update();
+
+  CheckLabelMapOverlap(filter->GetOutput());
+
+  out = LabelMapToLabelImage(filter->GetOutput());
+
+  EXPECT_EQ(MD5Hash(out.GetPointer()), "bef76c79168969548f1a8090d46b5f7e");
+  itk::WriteImage(out.GetPointer(), GetTestName() + "_on.png");
+}
+
+
+TEST_F(UniqueLabelMapFixture, Dilate2)
+{
+  const std::vector<typename FixtureUtilities<2>::IndexType> indices = { { 0, 0 }, { 1, 0 }, { 2, 0 }, { 3, 0 },
+                                                                         { 0, 4 }, { 2, 4 }, { 0, 5 } };
+  auto                                                       image = FixtureUtilities<2>::CreateLabelImage(indices);
+  auto labelMap = FixtureUtilities<2>::LabelMapFromLabelImage(image.GetPointer(), 2);
+
+  auto filter = itk::LabelUniqueLabelMapFilter<typename decltype(labelMap)::ObjectType>::New();
+  filter->SetInput(labelMap);
+  filter->InPlaceOff();
+  filter->ReverseOrderingOff();
+  filter->Update();
+
+  CheckLabelMapOverlap(filter->GetOutput());
+
+  auto out = LabelMapToLabelImage(filter->GetOutput());
+
+  EXPECT_EQ(MD5Hash(out.GetPointer()), "02ec62c193413dd82cb0feaee1ee0b12");
+  itk::WriteImage(out.GetPointer(), GetTestName() + "_off.png");
+
+
+  filter->ReverseOrderingOn();
+  filter->Update();
+
+  CheckLabelMapOverlap(filter->GetOutput());
+
+  out = LabelMapToLabelImage(filter->GetOutput());
+
+  EXPECT_EQ(MD5Hash(out.GetPointer()), "1c6901199b01ac095511792f447578a3");
+
+  itk::WriteImage(out.GetPointer(), GetTestName() + "_on.png");
+}