diff --git a/tools/workspace/curl_internal/cmakedefines.bzl b/tools/workspace/curl_internal/cmakedefines.bzl
index 67582cb0fa05..dda7e61310f4 100644
--- a/tools/workspace/curl_internal/cmakedefines.bzl
+++ b/tools/workspace/curl_internal/cmakedefines.bzl
@@ -126,6 +126,7 @@ CMAKE_DEFINES = [
     "HAVE_SIGNAL",
     "HAVE_SIGNAL_H",
     "HAVE_SIGSETJMP",
+    "HAVE_SNPRINTF",
     "HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID",
     "HAVE_SOCKET",
     "HAVE_SOCKETPAIR",
@@ -238,7 +239,6 @@ CMAKE_UNDEFINES = [
     "HAVE_TERMIO_H",
     "HAVE_UTIMES",
     "HAVE_WINDOWS_H",
-    "HAVE_WINLDAP_H",
     "HAVE_WINSOCK2_H",
     "HAVE_WS2TCPIP_H",
     "HAVE_ZSTD",
diff --git a/tools/workspace/curl_internal/package.BUILD.bazel b/tools/workspace/curl_internal/package.BUILD.bazel
index e2b7f7dd0393..62bfa6f36c81 100644
--- a/tools/workspace/curl_internal/package.BUILD.bazel
+++ b/tools/workspace/curl_internal/package.BUILD.bazel
@@ -89,6 +89,7 @@ _SRCS = [
     "lib/inet_ntop.c",
     "lib/inet_pton.c",
     "lib/llist.c",
+    "lib/macos.c",
     "lib/md4.c",
     "lib/md5.c",
     "lib/memdebug.c",
diff --git a/tools/workspace/curl_internal/repository.bzl b/tools/workspace/curl_internal/repository.bzl
index 12aa53b312b9..36519bd3fd96 100644
--- a/tools/workspace/curl_internal/repository.bzl
+++ b/tools/workspace/curl_internal/repository.bzl
@@ -10,8 +10,8 @@ def curl_internal_repository(
         In case of a cmake_configure_file build error when upgrading curl,
         update cmakedefines.bzl to match the new upstream definitions.
         """,
-        commit = "curl-8_1_2",
-        sha256 = "670d6aee0e32c687f7721a499e716d56fd1985eccb3186fe81a2f8097b4bc1fb",  # noqa
+        commit = "curl-8_2_1",
+        sha256 = "230d61a4b1eb3346930f2d601cc8fe5237957163e16befbe15e0ef40c56767a2",  # noqa
         build_file = ":package.BUILD.bazel",
         mirrors = mirrors,
     )