diff --git a/src/stac_auth_proxy/handlers/reverse_proxy.py b/src/stac_auth_proxy/handlers/reverse_proxy.py
index 3cae7137..5ace457f 100644
--- a/src/stac_auth_proxy/handlers/reverse_proxy.py
+++ b/src/stac_auth_proxy/handlers/reverse_proxy.py
@@ -45,6 +45,8 @@ def _prepare_headers(self, request: Request) -> MutableHeaders:
         proxy_proto = headers.get("X-Forwarded-Proto", request.url.scheme)
         proxy_host = headers.get("X-Forwarded-Host", request.url.netloc)
         proxy_path = headers.get("X-Forwarded-Path", request.base_url.path)
+        proxy_port = headers.get("X-Forwarded-Port")
+
         headers.setdefault(
             "Forwarded",
             f"for={proxy_client};host={proxy_host};proto={proxy_proto};path={proxy_path}",
@@ -57,6 +59,9 @@ def _prepare_headers(self, request: Request) -> MutableHeaders:
             headers.setdefault("X-Forwarded-Path", proxy_path)
             headers.setdefault("X-Forwarded-Proto", proxy_proto)
 
+        if proxy_port:
+            headers["X-Forwarded-Port"] = proxy_port
+
         # Set host to the upstream host
         if self.override_host:
             headers["Host"] = self.client.base_url.netloc.decode("utf-8")
diff --git a/tests/test_reverse_proxy.py b/tests/test_reverse_proxy.py
index bb840268..193a4b19 100644
--- a/tests/test_reverse_proxy.py
+++ b/tests/test_reverse_proxy.py
@@ -82,11 +82,13 @@ async def test_basic_headers(
         assert headers["X-Forwarded-Host"] == "localhost:8000"
         assert headers["X-Forwarded-Proto"] == "http"
         assert headers["X-Forwarded-Path"] == "/"
+        assert "X-Forwarded-Port" not in headers
     else:
         assert "X-Forwarded-For" not in headers
         assert "X-Forwarded-Host" not in headers
         assert "X-Forwarded-Proto" not in headers
         assert "X-Forwarded-Path" not in headers
+        assert "X-Forwarded-Port" not in headers
 
 
 @pytest.mark.parametrize("legacy_headers", [False, True])
@@ -113,11 +115,13 @@ async def test_forwarded_headers_with_client(mock_request, legacy_headers):
         assert headers["X-Forwarded-Host"] == "localhost:8000"
         assert headers["X-Forwarded-Proto"] == "http"
         assert headers["X-Forwarded-Path"] == "/"
+        assert "X-Forwarded-Port" not in headers
     else:
         assert "X-Forwarded-For" not in headers
         assert "X-Forwarded-Host" not in headers
         assert "X-Forwarded-Proto" not in headers
         assert "X-Forwarded-Path" not in headers
+        assert "X-Forwarded-Port" not in headers
 
 
 @pytest.mark.parametrize("legacy_headers", [False, True])
@@ -183,6 +187,7 @@ async def test_nginx_proxy_headers_preserved(legacy_headers):
     assert headers["X-Forwarded-Host"] == "api.example.com"
     assert headers["X-Forwarded-Proto"] == "https"
     assert headers["X-Forwarded-Path"] == "/api/v1"
+    assert "X-Forwarded-Port" not in headers
 
 
 @pytest.mark.parametrize(
@@ -282,3 +287,60 @@ async def test_nginx_headers_behavior(scope_overrides, headers, expected_forward
         assert f"{key}={expected_value}" in forwarded, (
             f"Expected {key}={expected_value} in {forwarded}"
         )
+
+
+@pytest.mark.parametrize("legacy_headers", [False, True])
+@pytest.mark.asyncio
+async def test_x_forwarded_port_forwarding(legacy_headers):
+    """Test that X-Forwarded-Port header is always forwarded if present in incoming request."""
+    headers = [
+        (b"host", b"localhost:8000"),
+        (b"x-forwarded-port", b"80"),
+        (b"x-forwarded-host", b"api.example.com"),
+        (b"x-forwarded-proto", b"http"),
+    ]
+    request = create_request(headers=headers)
+    handler = ReverseProxyHandler(
+        upstream="http://upstream-api.com", legacy_forwarded_headers=legacy_headers
+    )
+    result_headers = handler._prepare_headers(request)
+    assert result_headers["X-Forwarded-Port"] == "80"
+
+    if legacy_headers:
+        assert result_headers["X-Forwarded-Host"] == "api.example.com"
+        assert result_headers["X-Forwarded-Proto"] == "http"
+    else:
+        assert result_headers["X-Forwarded-Host"] == "api.example.com"
+        assert result_headers["X-Forwarded-Proto"] == "http"
+
+
+@pytest.mark.asyncio
+async def test_x_forwarded_port_not_added_when_missing():
+    """Test that X-Forwarded-Port is not added when not present in incoming request."""
+    headers = [
+        (b"host", b"localhost:8000"),
+        (b"x-forwarded-host", b"api.example.com"),
+        (b"x-forwarded-proto", b"http"),
+    ]
+    request = create_request(headers=headers)
+    handler = ReverseProxyHandler(
+        upstream="http://upstream-api.com", legacy_forwarded_headers=True
+    )
+    result_headers = handler._prepare_headers(request)
+    assert "X-Forwarded-Port" not in result_headers
+
+
+@pytest.mark.parametrize("legacy_headers", [False, True])
+@pytest.mark.asyncio
+async def test_x_forwarded_port_always_forwarded(legacy_headers):
+    """Test that X-Forwarded-Port is forwarded regardless of legacy_forwarded_headers setting."""
+    headers = [
+        (b"host", b"localhost:8000"),
+        (b"x-forwarded-port", b"443"),
+    ]
+    request = create_request(headers=headers)
+    handler = ReverseProxyHandler(
+        upstream="http://upstream-api.com", legacy_forwarded_headers=legacy_headers
+    )
+    result_headers = handler._prepare_headers(request)
+    assert result_headers["X-Forwarded-Port"] == "443"