diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8cd80f5dac..649e110433 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -46,6 +46,9 @@ Increment the:
   [#3320](https://github.com/open-telemetry/opentelemetry-cpp/pull/3220)
   [#3368](https://github.com/open-telemetry/opentelemetry-cpp/pull/3368)
 
+* [BUILD] Upgrade nlohmann_json to 3.12.0
+  [#3406](https://github.com/open-telemetry/opentelemetry-cpp/pull/3406)
+
 ## [1.20 2025-04-01]
 
 * [BUILD] Update opentelemetry-proto version
diff --git a/MODULE.bazel b/MODULE.bazel
index 4cc1a41bee..70f22d0173 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -12,7 +12,7 @@ bazel_dep(name = "abseil-cpp", version = "20240116.1", repo_name = "com_google_a
 bazel_dep(name = "bazel_skylib", version = "1.5.0")
 bazel_dep(name = "curl", version = "8.8.0")
 bazel_dep(name = "grpc", version = "1.63.1.bcr.1", repo_name = "com_github_grpc_grpc")
-bazel_dep(name = "nlohmann_json", version = "3.11.3", repo_name = "github_nlohmann_json")
+bazel_dep(name = "nlohmann_json", version = "3.12.0", repo_name = "github_nlohmann_json")
 bazel_dep(name = "opentelemetry-proto", version = "1.5.0", repo_name = "com_github_opentelemetry_proto")
 bazel_dep(name = "opentracing-cpp", version = "1.6.0", repo_name = "com_github_opentracing")
 bazel_dep(name = "platforms", version = "0.0.8")
diff --git a/bazel/repository.bzl b/bazel/repository.bzl
index 423db01fd1..e0424c665b 100644
--- a/bazel/repository.bzl
+++ b/bazel/repository.bzl
@@ -100,9 +100,9 @@ def opentelemetry_cpp_deps():
         http_archive,
         name = "github_nlohmann_json",
         build_file = "@io_opentelemetry_cpp//bazel:nlohmann_json.BUILD",
-        sha256 = "a22461d13119ac5c78f205d3df1db13403e58ce1bb1794edc9313677313f4a9d",
+        sha256 = "b8cb0ef2dd7f57f18933997c9934bb1fa962594f701cd5a8d3c2c80541559372",
         urls = [
-            "https://github.com/nlohmann/json/releases/download/v3.11.3/include.zip",
+            "https://github.com/nlohmann/json/releases/download/v3.12.0/include.zip",
         ],
     )
 
diff --git a/install/conan/conanfile_latest.txt b/install/conan/conanfile_latest.txt
index 9f2da4aab8..6db1d7b130 100644
--- a/install/conan/conanfile_latest.txt
+++ b/install/conan/conanfile_latest.txt
@@ -7,7 +7,7 @@ libcurl/8.12.1
 abseil/20240116.2
 protobuf/5.27.0
 grpc/1.67.1
-nlohmann_json/3.11.3
+nlohmann_json/3.12.0
 prometheus-cpp/1.3.0
 opentracing-cpp/1.6.0
 
@@ -37,4 +37,4 @@ CMakeToolchain
 CMakeDeps
 
 [layout]
-cmake_layout
\ No newline at end of file
+cmake_layout
diff --git a/third_party/nlohmann-json b/third_party/nlohmann-json
index 9cca280a4d..55f93686c0 160000
--- a/third_party/nlohmann-json
+++ b/third_party/nlohmann-json
@@ -1 +1 @@
-Subproject commit 9cca280a4d0ccf0c08f47a99aa71d1b0e52f8d03
+Subproject commit 55f93686c01528224f448c19128836e7df245f72
diff --git a/third_party_release b/third_party_release
index 37d6feb9f3..b3561a9a40 100644
--- a/third_party_release
+++ b/third_party_release
@@ -18,7 +18,7 @@ abseil=20240116.1
 benchmark=v1.8.3
 googletest=1.14.0
 ms-gsl=v3.1.0-67-g6f45293
-nlohmann-json=v3.11.3
+nlohmann-json=v3.12.0
 opentelemetry-proto=v1.5.0
 opentracing-cpp=v1.6.0
 prometheus-cpp=v1.3.0