diff --git a/cpp/src/arrow/flight/test-util.cc b/cpp/src/arrow/flight/test-util.cc
index 7b8a7f33cb8..becad1bf42e 100644
--- a/cpp/src/arrow/flight/test-util.cc
+++ b/cpp/src/arrow/flight/test-util.cc
@@ -119,9 +119,8 @@ bool TestServer::IsRunning() { return server_process_->running(); }
 int TestServer::port() const { return port_; }
 
 Status MakeFlightInfo(const Schema& schema, const FlightDescriptor& descriptor,
-                      const std::vector<FlightEndpoint>& endpoints,
-                      uint64_t total_records, uint64_t total_bytes,
-                      FlightInfo::Data* out) {
+                      const std::vector<FlightEndpoint>& endpoints, int64_t total_records,
+                      int64_t total_bytes, FlightInfo::Data* out) {
   out->descriptor = descriptor;
   out->endpoints = endpoints;
   out->total_records = total_records;
diff --git a/cpp/src/arrow/flight/test-util.h b/cpp/src/arrow/flight/test-util.h
index f955e3d7137..006c966c377 100644
--- a/cpp/src/arrow/flight/test-util.h
+++ b/cpp/src/arrow/flight/test-util.h
@@ -102,9 +102,8 @@ inline std::shared_ptr<Schema> ExampleSchema2() {
 
 ARROW_EXPORT
 Status MakeFlightInfo(const Schema& schema, const FlightDescriptor& descriptor,
-                      const std::vector<FlightEndpoint>& endpoints,
-                      uint64_t total_records, uint64_t total_bytes,
-                      FlightInfo::Data* out);
+                      const std::vector<FlightEndpoint>& endpoints, int64_t total_records,
+                      int64_t total_bytes, FlightInfo::Data* out);
 
 ARROW_EXPORT
 std::vector<FlightInfo> ExampleFlightInfo();
diff --git a/cpp/src/arrow/flight/types.h b/cpp/src/arrow/flight/types.h
index e4251bdd5d2..6db2655ef6c 100644
--- a/cpp/src/arrow/flight/types.h
+++ b/cpp/src/arrow/flight/types.h
@@ -119,8 +119,8 @@ class FlightInfo {
     std::string schema;
     FlightDescriptor descriptor;
     std::vector<FlightEndpoint> endpoints;
-    uint64_t total_records;
-    uint64_t total_bytes;
+    int64_t total_records;
+    int64_t total_bytes;
   };
 
   explicit FlightInfo(const Data& data) : data_(data), reconstructed_schema_(false) {}
@@ -141,10 +141,10 @@ class FlightInfo {
   const std::vector<FlightEndpoint>& endpoints() const { return data_.endpoints; }
 
   /// The total number of records (rows) in the dataset. If unknown, set to -1
-  uint64_t total_records() const { return data_.total_records; }
+  int64_t total_records() const { return data_.total_records; }
 
   /// The total number of bytes in the dataset. If unknown, set to -1
-  uint64_t total_bytes() const { return data_.total_bytes; }
+  int64_t total_bytes() const { return data_.total_bytes; }
 
  private:
   Data data_;
diff --git a/format/Flight.proto b/format/Flight.proto
index 219045b291c..3a6ae80ee25 100644
--- a/format/Flight.proto
+++ b/format/Flight.proto
@@ -230,8 +230,9 @@ message FlightGetInfo {
    */
   repeated FlightEndpoint endpoint = 3;
 
-  uint64 total_records = 4;
-  uint64 total_bytes = 5;
+  // Set these to -1 if unknown.
+  int64 total_records = 4;
+  int64 total_bytes = 5;
 }
 
 /*