diff --git a/MODULE.bazel b/MODULE.bazel
index 6f08aaec5e0e3..5d94b381410d4 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -31,7 +31,7 @@ bazel_dep(name = "abseil-cpp", version = "20250814.2")
 # See https://github.com/googleapis/google-cloud-cpp/issues/15393
 bazel_dep(name = "protobuf", version = "35.1", repo_name = "com_google_protobuf")
 bazel_dep(name = "boringssl", version = "0.20251124.0")
-bazel_dep(name = "nlohmann_json", version = "3.12.0.bcr.1")
+bazel_dep(name = "nlohmann_json", version = "3.12.0")
 bazel_dep(name = "curl", version = "8.8.0.bcr.3")
 bazel_dep(name = "opentelemetry-cpp", version = "1.24.0")
 bazel_dep(name = "rules_proto", version = "7.1.0")
diff --git a/bazel/workspace0.bzl b/bazel/workspace0.bzl
index 7712233406bed..3df3defff6e2a 100644
--- a/bazel/workspace0.bzl
+++ b/bazel/workspace0.bzl
@@ -252,10 +252,10 @@ def gl_cpp_workspace0(name = None):
         http_archive,
         name = "nlohmann_json",
         urls = [
-            "https://github.com/nlohmann/json/archive/v3.11.3.tar.gz",
+            "https://github.com/nlohmann/json/archive/v3.12.0.tar.gz",
         ],
-        sha256 = "0d8ef5af7f9794e3263480193c491549b2ba6cc74bb018906202ada498a79406",
-        strip_prefix = "json-3.11.3",
+        sha256 = "4b92eb0c06d10683f7447ce9406cb97cd4b453be18d7279320f7b2f025c10187",
+        strip_prefix = "json-3.12.0",
     )
 
     # Open Telemetry
diff --git a/ci/cloudbuild/dockerfiles/demo-rockylinux-9.Dockerfile b/ci/cloudbuild/dockerfiles/demo-rockylinux-9.Dockerfile
index 3a0bb01a8ba1b..7efde8950e673 100644
--- a/ci/cloudbuild/dockerfiles/demo-rockylinux-9.Dockerfile
+++ b/ci/cloudbuild/dockerfiles/demo-rockylinux-9.Dockerfile
@@ -187,7 +187,7 @@ RUN curl -fsSL https://github.com/grpc/grpc/archive/v1.71.2.tar.gz | \
 
 # ```bash
 WORKDIR /var/tmp/build/json
-RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.11.3.tar.gz | \
+RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.12.0.tar.gz | \
     tar -xzf - --strip-components=1 && \
     cmake \
       -DCMAKE_BUILD_TYPE=Debug \
diff --git a/ci/cloudbuild/dockerfiles/demo-ubuntu-jammy.Dockerfile b/ci/cloudbuild/dockerfiles/demo-ubuntu-jammy.Dockerfile
index 2e8278b2d3135..a71c12da1dc50 100644
--- a/ci/cloudbuild/dockerfiles/demo-ubuntu-jammy.Dockerfile
+++ b/ci/cloudbuild/dockerfiles/demo-ubuntu-jammy.Dockerfile
@@ -124,7 +124,7 @@ RUN curl -fsSL https://github.com/grpc/grpc/archive/v1.71.2.tar.gz | \
 
 # ```bash
 WORKDIR /var/tmp/build/json
-RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.11.3.tar.gz | \
+RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.12.0.tar.gz | \
     tar -xzf - --strip-components=1 && \
     cmake \
       -DCMAKE_BUILD_TYPE=Debug \
diff --git a/ci/cloudbuild/dockerfiles/fedora-cmake-quickstart.Dockerfile b/ci/cloudbuild/dockerfiles/fedora-cmake-quickstart.Dockerfile
index 40f84b4a7ffae..9b13886702448 100644
--- a/ci/cloudbuild/dockerfiles/fedora-cmake-quickstart.Dockerfile
+++ b/ci/cloudbuild/dockerfiles/fedora-cmake-quickstart.Dockerfile
@@ -134,7 +134,7 @@ RUN curl -fsSL https://github.com/google/benchmark/archive/v1.9.5.tar.gz | \
     ldconfig && cd /var/tmp && rm -fr build
 
 WORKDIR /var/tmp/build
-RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.11.3.tar.gz | \
+RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.12.0.tar.gz | \
     tar -xzf - --strip-components=1 && \
     cmake \
       -DCMAKE_BUILD_TYPE=Release \
diff --git a/ci/cloudbuild/dockerfiles/fedora-latest-cmake.Dockerfile b/ci/cloudbuild/dockerfiles/fedora-latest-cmake.Dockerfile
index c73462a758719..6ef4eb0269c39 100644
--- a/ci/cloudbuild/dockerfiles/fedora-latest-cmake.Dockerfile
+++ b/ci/cloudbuild/dockerfiles/fedora-latest-cmake.Dockerfile
@@ -134,7 +134,7 @@ RUN curl -fsSL https://github.com/google/benchmark/archive/v1.9.5.tar.gz | \
     ldconfig && cd /var/tmp && rm -fr build
 
 WORKDIR /var/tmp/build
-RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.11.3.tar.gz | \
+RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.12.0.tar.gz | \
     tar -xzf - --strip-components=1 && \
     cmake \
       -DCMAKE_BUILD_TYPE=Release \
diff --git a/ci/cloudbuild/dockerfiles/fedora-latest-cxx20.Dockerfile b/ci/cloudbuild/dockerfiles/fedora-latest-cxx20.Dockerfile
index d9aedb3c1cb81..5039a1ebf92e4 100644
--- a/ci/cloudbuild/dockerfiles/fedora-latest-cxx20.Dockerfile
+++ b/ci/cloudbuild/dockerfiles/fedora-latest-cxx20.Dockerfile
@@ -128,7 +128,7 @@ RUN curl -fsSL https://github.com/google/benchmark/archive/v1.9.5.tar.gz | \
     cd /var/tmp && rm -fr build
 
 WORKDIR /var/tmp/build
-RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.11.3.tar.gz | \
+RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.12.0.tar.gz | \
     tar -xzf - --strip-components=1 && \
     cmake \
       -DCMAKE_CXX_STANDARD=20 \
diff --git a/ci/cloudbuild/dockerfiles/fedora-m32.Dockerfile b/ci/cloudbuild/dockerfiles/fedora-m32.Dockerfile
index 0748c527de24f..fa52afd92abdc 100644
--- a/ci/cloudbuild/dockerfiles/fedora-m32.Dockerfile
+++ b/ci/cloudbuild/dockerfiles/fedora-m32.Dockerfile
@@ -105,7 +105,7 @@ RUN curl -fsSL https://github.com/curl/curl/releases/download/curl-8_7_1/curl-8.
 # Note that this is a header-only library, and often installed manually.
 # This leaves your environment without support for CMake pkg-config.
 WORKDIR /var/tmp/build/json
-RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.11.3.tar.gz | \
+RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.12.0.tar.gz | \
     tar -xzf - --strip-components=1 && \
     cmake \
       -DCMAKE_BUILD_TYPE=Release \
diff --git a/ci/cloudbuild/dockerfiles/gcc-oldest.Dockerfile b/ci/cloudbuild/dockerfiles/gcc-oldest.Dockerfile
index 28a5f9d5ed52a..a683bfe9e210f 100644
--- a/ci/cloudbuild/dockerfiles/gcc-oldest.Dockerfile
+++ b/ci/cloudbuild/dockerfiles/gcc-oldest.Dockerfile
@@ -136,7 +136,7 @@ RUN curl -fsSL https://github.com/grpc/grpc/archive/v1.81.0.tar.gz | \
     ldconfig && cd /var/tmp && rm -fr build
 
 WORKDIR /var/tmp/build
-RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.11.3.tar.gz | \
+RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.12.0.tar.gz | \
     tar -xzf - --strip-components=1 && \
     cmake \
       -DCMAKE_BUILD_TYPE=Release \
diff --git a/ci/cloudbuild/dockerfiles/ubuntu-20.04-install.Dockerfile b/ci/cloudbuild/dockerfiles/ubuntu-20.04-install.Dockerfile
index 618714e28bd77..ec75039811012 100644
--- a/ci/cloudbuild/dockerfiles/ubuntu-20.04-install.Dockerfile
+++ b/ci/cloudbuild/dockerfiles/ubuntu-20.04-install.Dockerfile
@@ -114,7 +114,7 @@ RUN curl -fsSL https://github.com/google/benchmark/archive/v1.9.5.tar.gz | \
     cd /var/tmp && rm -fr build
 
 WORKDIR /var/tmp/build/nlohmann-json
-RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.11.3.tar.gz | \
+RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.12.0.tar.gz | \
     tar -xzf - --strip-components=1 && \
     cmake \
       -DCMAKE_BUILD_TYPE="Release" \
diff --git a/ci/cloudbuild/dockerfiles/ubuntu-22.04-install.Dockerfile b/ci/cloudbuild/dockerfiles/ubuntu-22.04-install.Dockerfile
index f5324eabffe12..39ee9b8180eb5 100644
--- a/ci/cloudbuild/dockerfiles/ubuntu-22.04-install.Dockerfile
+++ b/ci/cloudbuild/dockerfiles/ubuntu-22.04-install.Dockerfile
@@ -113,7 +113,7 @@ RUN curl -fsSL https://github.com/google/benchmark/archive/v1.9.5.tar.gz | \
     cd /var/tmp && rm -fr build
 
 WORKDIR /var/tmp/build/nlohmann-json
-RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.11.3.tar.gz | \
+RUN curl -fsSL https://github.com/nlohmann/json/archive/v3.12.0.tar.gz | \
     tar -xzf - --strip-components=1 && \
     cmake \
       -DCMAKE_BUILD_TYPE="Release" \
diff --git a/doc/packaging.md b/doc/packaging.md
index 89d291a1a3cb4..47cdbc2963b8b 100644
--- a/doc/packaging.md
+++ b/doc/packaging.md
@@ -865,7 +865,7 @@ without support for CMake pkg-config.
 
 ```bash
 mkdir -p $HOME/Downloads/json && cd $HOME/Downloads/json
-curl -fsSL https://github.com/nlohmann/json/archive/v3.11.3.tar.gz | \
+curl -fsSL https://github.com/nlohmann/json/archive/v3.12.0.tar.gz | \
     tar -xzf - --strip-components=1 && \
     cmake \
       -DCMAKE_BUILD_TYPE=Debug \
@@ -1471,7 +1471,7 @@ without support for CMake pkg-config.
 
 ```bash
 mkdir -p $HOME/Downloads/json && cd $HOME/Downloads/json
-curl -fsSL https://github.com/nlohmann/json/archive/v3.11.3.tar.gz | \
+curl -fsSL https://github.com/nlohmann/json/archive/v3.12.0.tar.gz | \
     tar -xzf - --strip-components=1 && \
     cmake \
       -DCMAKE_BUILD_TYPE=Debug \