diff --git a/MODULE.bazel b/MODULE.bazel
index 7e0a6f99f4c1f..a728bef3a6b4c 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -26,7 +26,7 @@ bazel_dep(name = "rules_cc", version = "0.1.4")
 bazel_dep(name = "abseil-cpp", version = "20250127.1")
 bazel_dep(name = "protobuf", version = "31.1")
 bazel_dep(name = "boringssl", version = "0.0.0-20230215-5c22014")
-bazel_dep(name = "nlohmann_json", version = "3.11.3")
+bazel_dep(name = "nlohmann_json", version = "3.12.0")
 bazel_dep(name = "curl", version = "8.8.0.bcr.3")
 bazel_dep(name = "crc32c", version = "1.1.0")
 bazel_dep(name = "opentelemetry-cpp", version = "1.19.0")
diff --git a/bazel/workspace0.bzl b/bazel/workspace0.bzl
index 7e9392f3de039..54b663264bde3 100644
--- a/bazel/workspace0.bzl
+++ b/bazel/workspace0.bzl
@@ -219,10 +219,10 @@ def gl_cpp_workspace0(name = None):
         http_archive,
         name = "com_github_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",
     )
 
     # Load google/crc32c, a library to efficiently compute CRC32C checksums.
diff --git a/ci/cloudbuild/dockerfiles/demo-rockylinux-9.Dockerfile b/ci/cloudbuild/dockerfiles/demo-rockylinux-9.Dockerfile
index cdba691521388..a69c56c30af0b 100644
--- a/ci/cloudbuild/dockerfiles/demo-rockylinux-9.Dockerfile
+++ b/ci/cloudbuild/dockerfiles/demo-rockylinux-9.Dockerfile
@@ -180,7 +180,7 @@ RUN curl -fsSL https://github.com/google/crc32c/archive/1.1.2.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=Release \
diff --git a/ci/cloudbuild/dockerfiles/demo-ubuntu-focal.Dockerfile b/ci/cloudbuild/dockerfiles/demo-ubuntu-focal.Dockerfile
index e2f624dde7ff1..559fab39f1164 100644
--- a/ci/cloudbuild/dockerfiles/demo-ubuntu-focal.Dockerfile
+++ b/ci/cloudbuild/dockerfiles/demo-ubuntu-focal.Dockerfile
@@ -147,7 +147,7 @@ RUN curl -fsSL https://github.com/google/crc32c/archive/1.1.2.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=Release \
diff --git a/ci/cloudbuild/dockerfiles/demo-ubuntu-jammy.Dockerfile b/ci/cloudbuild/dockerfiles/demo-ubuntu-jammy.Dockerfile
index 8e996c4302dc9..b308fcf898e38 100644
--- a/ci/cloudbuild/dockerfiles/demo-ubuntu-jammy.Dockerfile
+++ b/ci/cloudbuild/dockerfiles/demo-ubuntu-jammy.Dockerfile
@@ -128,7 +128,7 @@ RUN curl -fsSL https://github.com/google/crc32c/archive/1.1.2.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=Release \
diff --git a/ci/cloudbuild/dockerfiles/fedora-latest-cmake.Dockerfile b/ci/cloudbuild/dockerfiles/fedora-latest-cmake.Dockerfile
index 08f008f9c09e3..5c8fb49da21ed 100644
--- a/ci/cloudbuild/dockerfiles/fedora-latest-cmake.Dockerfile
+++ b/ci/cloudbuild/dockerfiles/fedora-latest-cmake.Dockerfile
@@ -116,7 +116,7 @@ RUN curl -fsSL https://github.com/google/crc32c/archive/1.1.2.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 1072e33a83335..3a45528770aed 100644
--- a/ci/cloudbuild/dockerfiles/fedora-latest-cxx20.Dockerfile
+++ b/ci/cloudbuild/dockerfiles/fedora-latest-cxx20.Dockerfile
@@ -127,7 +127,7 @@ RUN curl -fsSL https://github.com/google/crc32c/archive/1.1.2.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 9582315c43d29..570b7a1a81a65 100644
--- a/ci/cloudbuild/dockerfiles/fedora-m32.Dockerfile
+++ b/ci/cloudbuild/dockerfiles/fedora-m32.Dockerfile
@@ -84,7 +84,7 @@ ENV PKG_CONFIG_PATH=/usr/local/share/pkgconfig:/usr/lib/pkgconfig
 # 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 ac01c42cd967e..7e95447dddc68 100644
--- a/ci/cloudbuild/dockerfiles/gcc-oldest.Dockerfile
+++ b/ci/cloudbuild/dockerfiles/gcc-oldest.Dockerfile
@@ -131,7 +131,7 @@ RUN curl -fsSL https://github.com/grpc/grpc/archive/v1.71.0.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 f745e22b5b6f6..3a62be22ac1fc 100644
--- a/ci/cloudbuild/dockerfiles/ubuntu-20.04-install.Dockerfile
+++ b/ci/cloudbuild/dockerfiles/ubuntu-20.04-install.Dockerfile
@@ -111,7 +111,7 @@ RUN curl -fsSL https://github.com/google/crc32c/archive/1.1.2.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 9880ed0bc577b..c6c5401a493d2 100644
--- a/doc/packaging.md
+++ b/doc/packaging.md
@@ -661,7 +661,7 @@ 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=Release \
@@ -852,7 +852,7 @@ 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=Release \
@@ -1368,7 +1368,7 @@ 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=Release \