diff --git a/.github/workflows/benchmark.yml b/.github/workflows/benchmark.yml
index 18c29605c96..9877d7ca989 100644
--- a/.github/workflows/benchmark.yml
+++ b/.github/workflows/benchmark.yml
@@ -4,7 +4,7 @@ on:
     branches:
       - main
 env:
-  DEFAULT_GO_VERSION: "1.20"
+  DEFAULT_GO_VERSION: "1.21"
 jobs:
   benchmark:
     name: Benchmarks
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index cc6290a5e72..a0dc91bfea2 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -14,7 +14,7 @@ env:
   # backwards compatibility with the previous two minor releases and we
   # explicitly test our code for these versions so keeping this at prior
   # versions does not add value.
-  DEFAULT_GO_VERSION: "1.20"
+  DEFAULT_GO_VERSION: "1.21"
 jobs:
   lint:
     runs-on: ubuntu-latest
@@ -99,7 +99,7 @@ jobs:
   compatibility-test:
     strategy:
       matrix:
-        go-version: ["1.20", 1.19]
+        go-version: ["1.21", "1.20", 1.19]
         os: [ubuntu-latest, macos-latest, windows-latest]
         # GitHub Actions does not support arm* architectures on default
         # runners. It is possible to accomplish this with a self-hosted runner
diff --git a/.github/workflows/dependabot.yml b/.github/workflows/dependabot.yml
index 2de6b06d401..9d4e27a9e6e 100644
--- a/.github/workflows/dependabot.yml
+++ b/.github/workflows/dependabot.yml
@@ -13,7 +13,7 @@ jobs:
         ref: ${{ github.head_ref }}
     - uses: actions/setup-go@v4
       with:
-        go-version: '^1.20.0'
+        go-version: '^1.21.0'
     - uses: evantorrie/mott-the-tidier@v1-beta
       id: modtidy
       with:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 12acf1a39c6..7b718896178 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,6 +27,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Move the `Aggregation` interface and its implementations from `go.opentelemetry.io/otel/sdk/metric/aggregation` to `go.opentelemetry.io/otel/sdk/metric`. (#4435)
 - The exporters in `go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc` and `go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp` support the `OTEL_EXPORTER_OTLP_METRICS_DEFAULT_HISTOGRAM_AGGREGATION` environment variable. (#4437)
 - Add the `NewAllowKeysFilter` and `NewDenyKeysFilter` functions to `go.opentelemetry.io/otel/attribute` to allow convenient creation of allow-keys and deny-keys filters. (#4444)
+- Support Go 1.21. (#4463)
 
 ### Changed
 
diff --git a/README.md b/README.md
index 652dd175590..4e5531f3052 100644
--- a/README.md
+++ b/README.md
@@ -53,14 +53,19 @@ Currently, this project supports the following environments.
 
 | OS      | Go Version | Architecture |
 |---------|------------|--------------|
+| Ubuntu  | 1.21       | amd64        |
 | Ubuntu  | 1.20       | amd64        |
 | Ubuntu  | 1.19       | amd64        |
+| Ubuntu  | 1.21       | 386          |
 | Ubuntu  | 1.20       | 386          |
 | Ubuntu  | 1.19       | 386          |
+| MacOS   | 1.21       | amd64        |
 | MacOS   | 1.20       | amd64        |
 | MacOS   | 1.19       | amd64        |
+| Windows | 1.21       | amd64        |
 | Windows | 1.20       | amd64        |
 | Windows | 1.19       | amd64        |
+| Windows | 1.21       | 386          |
 | Windows | 1.20       | 386          |
 | Windows | 1.19       | 386          |