diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerRequest.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerRequest.java
index f0a1e520cb3..f386a3abfc5 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerRequest.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerRequest.java
@@ -33,6 +33,7 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.Enumeration;
 import java.util.Iterator;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
@@ -443,7 +444,7 @@ class DefaultServerRequest implements ServerRequest {
 						List<String> value = Arrays.asList(entry.getValue());
 						return new SimpleImmutableEntry<>(entry.getKey(), value);
 					})
-					.collect(Collectors.toSet());
+					.collect(Collectors.toCollection(LinkedHashSet::new));
 		}
 
 		@Override
diff --git a/spring-webmvc/src/test/java/org/springframework/web/servlet/function/DefaultServerRequestTests.java b/spring-webmvc/src/test/java/org/springframework/web/servlet/function/DefaultServerRequestTests.java
index 63256433b16..81ee930ba5c 100644
--- a/spring-webmvc/src/test/java/org/springframework/web/servlet/function/DefaultServerRequestTests.java
+++ b/spring-webmvc/src/test/java/org/springframework/web/servlet/function/DefaultServerRequestTests.java
@@ -167,6 +167,20 @@ class DefaultServerRequestTests {
 		assertThat(request.param("foo")).contains("bar");
 	}
 
+	@Test  // gh-36966
+	void paramsEntrySetPreservesOrder() {
+		MockHttpServletRequest servletRequest = PathPatternsTestUtils.initRequest("GET", "/", true);
+		servletRequest.setParameter("charlie", "3");
+		servletRequest.setParameter("alpha", "1");
+		servletRequest.setParameter("bravo", "2");
+
+		DefaultServerRequest request = new DefaultServerRequest(servletRequest, this.messageConverters);
+
+		assertThat(request.params().entrySet())
+				.extracting(Map.Entry::getKey)
+				.containsExactly("charlie", "alpha", "bravo");
+	}
+
 	@Test
 	void multipartData() throws Exception {
 		MockPart formPart = new MockPart("form", "foo".getBytes(UTF_8));