diff --git a/lib/src/extensions/matches_request.dart b/lib/src/extensions/matches_request.dart
index 3665e63..8af0e95 100644
--- a/lib/src/extensions/matches_request.dart
+++ b/lib/src/extensions/matches_request.dart
@@ -8,9 +8,10 @@ import 'package:http_mock_adapter/src/types.dart';
 extension MatchesRequest on RequestOptions {
   /// Check values against matchers.
   /// [request] is the configured [Request] which would contain the matchers if used.
-  bool matchesRequest(Request request) {
+  bool matchesRequest(Request request, bool needsExactBody) {
     final routeMatched = doesRouteMatch(path, request.route);
-    final requestBodyMatched = matches(data, request.data);
+    final requestBodyMatched =
+        matches(data, request.data, exactMaps: needsExactBody);
     final queryParametersMatched =
         matches(queryParameters, request.queryParameters ?? {});
     final headersMatched = matches(headers, request.headers ?? {});
@@ -46,7 +47,7 @@ extension MatchesRequest on RequestOptions {
   }
 
   /// Check the map keys and values determined by the definition.
-  bool matches(dynamic actual, dynamic expected) {
+  bool matches(dynamic actual, dynamic expected, {bool exactMaps = false}) {
     if (actual == null && expected == null) {
       return true;
     }
@@ -60,6 +61,11 @@ extension MatchesRequest on RequestOptions {
         return false;
       }
     } else if (actual is Map && expected is Map) {
+      // If exactMap is true, ensure that actual and expected have the same length.
+      if (exactMaps && actual.length != expected.length) {
+        return false;
+      }
+
       for (final key in expected.keys.toList()) {
         if (!actual.containsKey(key)) {
           return false;
@@ -71,7 +77,7 @@ extension MatchesRequest on RequestOptions {
         } else if (expected[key] != actual[key]) {
           // Exact match unless map.
           if (expected[key] is Map && actual[key] is Map) {
-            if (!matches(actual[key], expected[key])) {
+            if (!matches(actual[key], expected[key], exactMaps: exactMaps)) {
               // Allow maps to use matchers.
               return false;
             }
@@ -82,6 +88,11 @@ extension MatchesRequest on RequestOptions {
           }
         }
       }
+
+      // If exactMap is true, check that there are no keys in actual that are not in expected.
+      if (exactMaps && actual.keys.any((key) => !expected.containsKey(key))) {
+        return false;
+      }
     } else if (actual is List && expected is List) {
       for (var index in Iterable.generate(actual.length)) {
         if (!matches(actual[index], expected[index])) {
diff --git a/lib/src/matchers/http_matcher.dart b/lib/src/matchers/http_matcher.dart
index 3c5b337..d34402f 100644
--- a/lib/src/matchers/http_matcher.dart
+++ b/lib/src/matchers/http_matcher.dart
@@ -26,11 +26,12 @@ abstract class HttpRequestMatcher {
 /// class.
 ///
 class FullHttpRequestMatcher extends HttpRequestMatcher {
-  const FullHttpRequestMatcher();
+  final bool needsExactBody;
+  const FullHttpRequestMatcher({this.needsExactBody = false});
 
   @override
   bool matches(RequestOptions ongoingRequest, Request matcher) {
-    return ongoingRequest.matchesRequest(matcher);
+    return ongoingRequest.matchesRequest(matcher, needsExactBody);
   }
 }
 
diff --git a/test/extensions/matches_request_test.dart b/test/extensions/matches_request_test.dart
index 34cb55d..c4ef3d4 100644
--- a/test/extensions/matches_request_test.dart
+++ b/test/extensions/matches_request_test.dart
@@ -21,7 +21,7 @@ void main() {
         queryParameters: <String, dynamic>{},
       );
 
-      expect(options.matchesRequest(request), true);
+      expect(options.matchesRequest(request, false), true);
     });
 
     group('matches', () {
@@ -251,6 +251,105 @@ void main() {
                   e.error is AssertionError)));
         });
       });
+
+      group('Exact body matches', () {
+        late Dio dio;
+        late DioAdapter dioAdapter;
+
+        setUpAll(() {
+          dio = Dio(BaseOptions(contentType: Headers.jsonContentType));
+          dioAdapter = DioAdapter(
+            dio: dio,
+            matcher: const FullHttpRequestMatcher(needsExactBody: true),
+          );
+        });
+
+        test(
+            'does not match requests via onPost() when expected body is subset of actual body',
+            () async {
+          dioAdapter.onPost(
+            '/too-many-fields',
+            (server) => server.reply(200, 'OK'),
+            data: {
+              'expected': {
+                'nestedExpected': 'value',
+              },
+            },
+          );
+
+          final data = {
+            'expected': {
+              'nestedExpected': 'value',
+              'nestedUnexpected': 'value',
+            },
+            'unexepected': 'value'
+          };
+          expect(
+            () => dio.post('/too-many-fields', data: data),
+            throwsA(
+              predicate((e) =>
+                  e is DioException &&
+                  e.type == DioExceptionType.unknown &&
+                  e.error is AssertionError),
+            ),
+          );
+        });
+        test(
+            'does not match requests via onPost() when actual body is subset of expected body',
+            () async {
+          dioAdapter.onPost(
+            '/not-enough-fields',
+            (server) => server.reply(200, 'OK'),
+            data: {
+              'expected': {
+                'nestedExpected': 'value',
+                'nestedUnexpected': 'value',
+              },
+              'unexepected': 'value'
+            },
+          );
+
+          final data = {
+            'expected': {
+              'nestedExpected': 'value',
+            },
+          };
+          expect(
+            () => dio.post('/not-enough-fields', data: data),
+            throwsA(
+              predicate((e) =>
+                  e is DioException &&
+                  e.type == DioExceptionType.unknown &&
+                  e.error is AssertionError),
+            ),
+          );
+        });
+        test(
+            'does match requests via onPost() when expected body is equal to actual body',
+            () async {
+          dioAdapter.onPost(
+            '/post-exact-data',
+            (server) => server.reply(200, 'OK'),
+            data: {
+              'expected': {
+                'nestedExpected': 'value',
+                'nestedUnexpected': 'value',
+              },
+              'unexepected': 'value'
+            },
+          );
+
+          var response = await dio.post('/post-exact-data', data: {
+            'expected': {
+              'nestedExpected': 'value',
+              'nestedUnexpected': 'value',
+            },
+            'unexepected': 'value'
+          });
+
+          expect(response.data, 'OK');
+        });
+      });
     });
   });
 }