diff --git a/pyproject.toml b/pyproject.toml
index 5bc1f88..3bc9496 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "labelformat"
-version = "0.1.15"
+version = "0.1.16"
 authors = [{ name = "Lightly.ai" }]
 description = "A tool for converting computer vision label formats."
 readme = "README.md"
diff --git a/src/labelformat/formats/coco.py b/src/labelformat/formats/coco.py
index fdb9df6..fbde286 100644
--- a/src/labelformat/formats/coco.py
+++ b/src/labelformat/formats/coco.py
@@ -90,6 +90,7 @@ def get_labels(self) -> Iterable[ImageObjectDetection]:
                             bbox=[float(x) for x in ann["bbox"]],
                             format=BoundingBoxFormat.XYWH,
                         ),
+                        confidence=(float(ann["score"]) if "score" in ann else None),
                     )
                 )
             yield ImageObjectDetection(
@@ -173,6 +174,8 @@ def save(self, label_input: ObjectDetectionInput) -> None:
                         float(v) for v in obj.box.to_format(BoundingBoxFormat.XYWH)
                     ],
                 }
+                if obj.confidence is not None:
+                    annotation["score"] = obj.confidence
                 data["annotations"].append(annotation)
 
         self.output_file.parent.mkdir(parents=True, exist_ok=True)
diff --git a/tests/unit/formats/test_coco.py b/tests/unit/formats/test_coco.py
new file mode 100644
index 0000000..c0805c6
--- /dev/null
+++ b/tests/unit/formats/test_coco.py
@@ -0,0 +1,101 @@
+import json
+from pathlib import Path
+
+import pytest
+
+from labelformat.formats.coco import COCOObjectDetectionInput, COCOObjectDetectionOutput
+from labelformat.model.bounding_box import BoundingBox
+from labelformat.model.category import Category
+from labelformat.model.image import Image
+from labelformat.model.object_detection import (
+    ImageObjectDetection,
+    SingleObjectDetection,
+)
+
+from ... import simple_object_detection_label_input
+
+
+def _create_coco_file(tmp_path: Path, with_score: bool) -> Path:
+    annotations = [
+        {
+            "image_id": 0,
+            "category_id": 1,
+            "bbox": [10.0, 20.0, 20.0, 20.0],
+        },
+        {
+            "image_id": 0,
+            "category_id": 0,
+            "bbox": [50.0, 60.0, 20.0, 20.0],
+        },
+    ]
+    if with_score:
+        annotations[0]["score"] = 0.4
+        annotations[1]["score"] = 0.8
+    data = {
+        "images": [
+            {"id": 0, "file_name": "image.jpg", "width": 100, "height": 200},
+        ],
+        "categories": [
+            {"id": 0, "name": "cat"},
+            {"id": 1, "name": "dog"},
+            {"id": 2, "name": "cow"},
+        ],
+        "annotations": annotations,
+    }
+    coco_file = tmp_path / "train.json"
+    coco_file.write_text(json.dumps(data))
+    return coco_file
+
+
+class TestCOCOObjectDetectionInput:
+    @pytest.mark.parametrize("with_score", [True, False])
+    def test_get_labels(self, tmp_path: Path, with_score: bool) -> None:
+        coco_file = _create_coco_file(tmp_path=tmp_path, with_score=with_score)
+        label_input = COCOObjectDetectionInput(input_file=coco_file)
+        labels = list(label_input.get_labels())
+        assert labels == [
+            ImageObjectDetection(
+                image=Image(id=0, filename="image.jpg", width=100, height=200),
+                objects=[
+                    SingleObjectDetection(
+                        category=Category(id=1, name="dog"),
+                        box=BoundingBox(xmin=10.0, ymin=20.0, xmax=30.0, ymax=40.0),
+                        confidence=0.4 if with_score else None,
+                    ),
+                    SingleObjectDetection(
+                        category=Category(id=0, name="cat"),
+                        box=BoundingBox(xmin=50.0, ymin=60.0, xmax=70.0, ymax=80.0),
+                        confidence=0.8 if with_score else None,
+                    ),
+                ],
+            ),
+        ]
+
+
+class TestCOCOObjectDetectionOutput:
+    @pytest.mark.parametrize("with_confidence", [True, False])
+    def test_save(self, tmp_path: Path, with_confidence: bool) -> None:
+        output_file = tmp_path / "train.json"
+        COCOObjectDetectionOutput(output_file=output_file).save(
+            label_input=simple_object_detection_label_input.get_input(
+                with_confidence=with_confidence
+            )
+        )
+
+        output_json = json.loads(output_file.read_text())
+        expected_annotations = [
+            {
+                "image_id": 0,
+                "category_id": 1,
+                "bbox": [10.0, 20.0, 20.0, 20.0],
+            },
+            {
+                "image_id": 0,
+                "category_id": 0,
+                "bbox": [50.0, 60.0, 20.0, 20.0],
+            },
+        ]
+        if with_confidence:
+            expected_annotations[0]["score"] = 0.4
+            expected_annotations[1]["score"] = 0.8
+        assert output_json["annotations"] == expected_annotations
diff --git a/uv.lock b/uv.lock
index 1d0a508..1b84305 100644
--- a/uv.lock
+++ b/uv.lock
@@ -2706,7 +2706,7 @@ wheels = [
 
 [[package]]
 name = "labelformat"
-version = "0.1.15"
+version = "0.1.16"
 source = { editable = "." }
 dependencies = [
     { name = "fsspec", version = "2024.10.0", source = { registry = "https://pypi.org/simple" }, marker = "python_full_version < '3.9'" },