diff --git a/spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/ResponseEntityResultHandler.java b/spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/ResponseEntityResultHandler.java
index f581ab295e7..ac1331969ef 100644
--- a/spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/ResponseEntityResultHandler.java
+++ b/spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/ResponseEntityResultHandler.java
@@ -155,7 +155,6 @@ public class ResponseEntityResultHandler extends AbstractMessageWriterResultHand
 			HttpHeaders responseHeaders = exchange.getResponse().getHeaders();
 			if (!entityHeaders.isEmpty()) {
 				entityHeaders.entrySet().stream()
-						.filter(entry -> !responseHeaders.containsKey(entry.getKey()))
 						.forEach(entry -> responseHeaders.put(entry.getKey(), entry.getValue()));
 			}
 
diff --git a/spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ResponseEntityResultHandlerTests.java b/spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ResponseEntityResultHandlerTests.java
index a3f3c7255a3..7be305b9996 100644
--- a/spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ResponseEntityResultHandlerTests.java
+++ b/spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ResponseEntityResultHandlerTests.java
@@ -44,6 +44,7 @@ import org.springframework.core.io.buffer.support.DataBufferTestUtils;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
 import org.springframework.http.codec.EncoderHttpMessageWriter;
 import org.springframework.http.codec.HttpMessageWriter;
@@ -334,6 +335,22 @@ public class ResponseEntityResultHandlerTests {
 		assertResponseBodyIsEmpty(exchange);
 	}
 
+	@Test // SPR-17082
+	public void handleResponseEntityWithExistingResponseHeaders() throws Exception {
+		ResponseEntity<Void> value = ResponseEntity.ok().contentType(MediaType.APPLICATION_JSON).build();
+		MethodParameter returnType = on(TestController.class).resolveReturnType(entity(Void.class));
+		HandlerResult result = handlerResult(value, returnType);
+		MockServerWebExchange exchange = MockServerWebExchange.from(get("/path"));
+		exchange.getResponse().getHeaders().setContentType(MediaType.TEXT_PLAIN);
+		this.resultHandler.handleResult(exchange, result).block(Duration.ofSeconds(5));
+
+		assertEquals(HttpStatus.OK, exchange.getResponse().getStatusCode());
+		assertEquals(1, exchange.getResponse().getHeaders().size());
+		assertEquals(MediaType.APPLICATION_JSON, exchange.getResponse().getHeaders().getContentType());
+		assertResponseBodyIsEmpty(exchange);
+	}
+
+
 
 	private void testHandle(Object returnValue, MethodParameter returnType) {
 		MockServerWebExchange exchange = MockServerWebExchange.from(get("/path"));