diff --git a/README.md b/README.md
index 3ace170..d178904 100644
--- a/README.md
+++ b/README.md
@@ -17,6 +17,7 @@ bumps, changelogs, tags, and GitHub releases. Optionally gate releases behind a
 - **Optional release gating** — require a label on a PR before it triggers a release
 - **GitHub releases** — auto-generated release notes, draft or published
 - **npm publishing** — token-based or [npm Trusted Publishers](https://docs.npmjs.com/trusted-publishers) (OIDC)
+- **Monorepo support** — publish every npm-workspaces package together with fixed (locked) versioning
 - **GitHub Packages support** — point at any npm-compatible registry
 - **Composite action** — runs as bash on the consumer's runner, no Docker pull
 
@@ -118,6 +119,7 @@ jobs:
 | `npm-token`             | Auth token for the npm registry. Omit to use [Trusted Publishers](#publish-to-npm-with-trusted-publishers) (OIDC) | No       | —                            |
 | `npm-registry`          | npm registry URL (set to `https://npm.pkg.github.com` for GitHub Packages)                                        | No       | `https://registry.npmjs.org` |
 | `npm-build-command`     | Build command to run before `npm publish` (e.g., `npm run build`)                                                 | No       | —                            |
+| `npm-workspaces`        | Publish every npm workspace package (monorepo). All packages share one version — see [Publish a monorepo](#publish-a-monorepo-npm-workspaces) | No       | `false`                      |
 
 ## Outputs
 
@@ -279,6 +281,44 @@ jobs:
     npm-build-command: 'npm run build'
 ```
 
+### Publish a monorepo (npm workspaces)
+
+Set `npm-workspaces: true` to publish every package in an npm-workspaces monorepo. Release Champion uses
+**fixed (locked) versioning**: it computes a single version from your conventional commits, then bumps and publishes
+**every** package to that same version. There is still one tag, one release PR, and one root `CHANGELOG.md`.
+
+```yaml
+- uses: offload-project/release-champion@v1
+  with:
+    github-token: ${{ secrets.GITHUB_TOKEN }}
+    publish-npm: true
+    npm-workspaces: true
+    npm-token: ${{ secrets.NPM_TOKEN }}
+    npm-build-command: 'npm run build'
+```
+
+Packages are discovered from the `workspaces` field in your root `package.json` (both the array and
+`{ "packages": [...] }` forms are supported):
+
+```json
+{
+  "name": "my-monorepo",
+  "private": true,
+  "workspaces": ["packages/*"]
+}
+```
+
+Behavior notes:
+
+- **One version for all.** A change to any package bumps and republishes every package — even packages that didn't
+  change. (If you need each package to version independently, that isn't supported yet.)
+- **Private packages are skipped.** Any package with `"private": true` is bumped but never published — so a private
+  root `package.json` that only declares `workspaces` is handled correctly.
+- **Scoped packages publish publicly.** Packages with a scoped name (`@scope/name`) are published with
+  `--access public` so first publishes don't fail. Restricted scoped packages aren't supported.
+- **Trusted Publishers per package.** OIDC publishing works, but each package must be registered as its own trusted
+  publisher on npm.
+
 ### Tag only, no GitHub release
 
 ```yaml
diff --git a/action.yml b/action.yml
index 701ae36..cd78aa2 100644
--- a/action.yml
+++ b/action.yml
@@ -50,6 +50,10 @@ inputs:
   npm-build-command:
     description: 'Build command to run before npm publish (e.g., npm run build)'
     required: false
+  npm-workspaces:
+    description: 'Publish every npm workspace package (monorepo, fixed/locked versioning). All packages share the single computed version. Discovered from the root package.json "workspaces" field.'
+    required: false
+    default: 'false'
 
 outputs:
   version:
@@ -84,6 +88,7 @@ runs:
         INPUT_NPM_TOKEN: ${{ inputs.npm-token }}
         INPUT_NPM_REGISTRY: ${{ inputs.npm-registry }}
         INPUT_NPM_BUILD_COMMAND: ${{ inputs.npm-build-command }}
+        INPUT_NPM_WORKSPACES: ${{ inputs.npm-workspaces }}
         PR_NUMBER: ${{ github.event.pull_request.number }}
         PR_HEAD_REF: ${{ github.event.pull_request.head.ref }}
         PR_MERGED: ${{ github.event.pull_request.merged }}
diff --git a/scripts/create-release-pr.sh b/scripts/create-release-pr.sh
index f21307f..309929a 100755
--- a/scripts/create-release-pr.sh
+++ b/scripts/create-release-pr.sh
@@ -6,6 +6,7 @@ set -euo pipefail
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 source "$SCRIPT_DIR/conventional.sh"
 source "$SCRIPT_DIR/changelog.sh"
+source "$SCRIPT_DIR/workspaces.sh"
 
 main() {
   echo "::group::Analyzing commits for version bump"
@@ -66,9 +67,26 @@ main() {
       echo "::error::publish-npm is enabled but no package.json found"
       exit 1
     fi
-    echo "Bumping package.json to ${new_version}"
-    npm version "$new_version" --no-git-tag-version
-    git add package.json
+
+    # In fixed/locked mode every workspace package shares the new version. The
+    # root package.json is always bumped (it carries the workspaces field); each
+    # discovered workspace package is bumped to the same version.
+    local bump_dirs=(".")
+    if [[ "${INPUT_NPM_WORKSPACES:-false}" == "true" ]]; then
+      local pkg_dir
+      while IFS= read -r pkg_dir; do
+        [[ -n "$pkg_dir" ]] && bump_dirs+=("$pkg_dir")
+      done < <(discover_packages ".")
+      echo "Workspaces mode: bumping ${#bump_dirs[@]} package(s) to ${new_version}"
+    fi
+
+    local dir
+    for dir in "${bump_dirs[@]}"; do
+      echo "Bumping ${dir}/package.json to ${new_version}"
+      ( cd "$dir" && npm version "$new_version" --no-git-tag-version --allow-same-version )
+      git add "$dir/package.json"
+    done
+
     if [[ -f package-lock.json ]] && ! git diff --staged --quiet package-lock.json 2>/dev/null; then
       git add package-lock.json
     fi
diff --git a/scripts/finalize-release.sh b/scripts/finalize-release.sh
index 24c4122..3c35bce 100755
--- a/scripts/finalize-release.sh
+++ b/scripts/finalize-release.sh
@@ -5,6 +5,7 @@ set -euo pipefail
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 source "$SCRIPT_DIR/conventional.sh"
+source "$SCRIPT_DIR/workspaces.sh"
 
 main() {
   # Extract version from branch name (release/v1.2.3 → v1.2.3)
@@ -87,13 +88,40 @@ main() {
       eval "$INPUT_NPM_BUILD_COMMAND"
     fi
 
-    npm publish
+    # Build the list of package directories to publish. In fixed/locked
+    # workspaces mode this is the root plus every discovered workspace package;
+    # otherwise it is just the root.
+    local publish_dirs=(".")
+    if [[ "${INPUT_NPM_WORKSPACES:-false}" == "true" ]]; then
+      local pkg_dir
+      while IFS= read -r pkg_dir; do
+        [[ -n "$pkg_dir" ]] && publish_dirs+=("$pkg_dir")
+      done < <(discover_packages ".")
+    fi
 
-    rm -f .npmrc
+    # Publish each package from the repo root so the root .npmrc auth applies
+    # (npm only reads the project .npmrc from the current directory). Private
+    # packages are skipped; scoped names get --access public for first publish.
+    local dir
+    for dir in "${publish_dirs[@]}"; do
+      if is_private_package "$dir"; then
+        echo "Skipping ${dir} (private package)"
+        continue
+      fi
+
+      local publish_flags=("$dir")
+      if is_scoped_package "$dir"; then
+        publish_flags+=(--access public)
+      fi
 
-    local pkg_name
-    pkg_name=$(node -p "require('./package.json').name")
-    echo "Published ${pkg_name}@${version}"
+      npm publish "${publish_flags[@]}"
+
+      local pkg_name
+      pkg_name=$(node -e 'const fs=require("fs");console.log(JSON.parse(fs.readFileSync(process.argv[1],"utf8")).name)' "$dir/package.json")
+      echo "Published ${pkg_name}@${version}"
+    done
+
+    rm -f .npmrc
     echo "::endgroup::"
   fi
 
diff --git a/scripts/workspaces.sh b/scripts/workspaces.sh
new file mode 100644
index 0000000..dba42f1
--- /dev/null
+++ b/scripts/workspaces.sh
@@ -0,0 +1,78 @@
+#!/usr/bin/env bash
+# Workspace discovery for monorepo (fixed/locked) publishing.
+#
+# "Fixed mode" means every package shares the single version computed from
+# conventional commits — there is still one tag and one CHANGELOG.md. These
+# helpers only answer two questions: which package directories exist, and which
+# of those are publishable.
+
+set -euo pipefail
+
+# Read the workspace glob patterns from a package.json's "workspaces" field.
+# Handles both the array form (["packages/*"]) and the object form
+# ({ "packages": ["packages/*"] }). Emits one pattern per line; emits nothing
+# when there is no workspaces field.
+# Usage: read_workspace_patterns [package.json path]
+read_workspace_patterns() {
+  local pkg_json="${1:-package.json}"
+  [[ -f "$pkg_json" ]] || return 0
+
+  node -e '
+    const fs = require("fs");
+    const pkg = JSON.parse(fs.readFileSync(process.argv[1], "utf8"));
+    let ws = pkg.workspaces;
+    if (!ws) process.exit(0);
+    if (!Array.isArray(ws)) ws = ws.packages || [];
+    for (const p of ws) console.log(p);
+  ' "$pkg_json"
+}
+
+# Discover all workspace package directories under a root.
+# Expands each workspace glob and emits every directory that contains a
+# package.json. Emits nothing when the root declares no workspaces.
+# Usage: discover_packages [root dir]
+discover_packages() {
+  local root="${1:-.}"
+  local patterns
+  patterns=$(read_workspace_patterns "$root/package.json")
+  [[ -z "$patterns" ]] && return 0
+
+  local pattern dir
+  # nullglob so a pattern that matches nothing expands to nothing rather than
+  # the literal glob string.
+  shopt -s nullglob
+  while IFS= read -r pattern; do
+    [[ -z "$pattern" ]] && continue
+    for dir in "$root"/$pattern/; do
+      dir="${dir%/}"
+      [[ -f "$dir/package.json" ]] && echo "$dir"
+    done
+  done <<< "$patterns"
+  shopt -u nullglob
+}
+
+# Whether a package directory is marked private (and therefore must not be
+# published). Returns success (0) when private.
+# Usage: is_private_package <dir>
+is_private_package() {
+  local dir="$1"
+  [[ -f "$dir/package.json" ]] || return 1
+  node -e '
+    const fs = require("fs");
+    const pkg = JSON.parse(fs.readFileSync(process.argv[1], "utf8"));
+    process.exit(pkg.private === true ? 0 : 1);
+  ' "$dir/package.json"
+}
+
+# Whether a package has a scoped name (@scope/name), which npm publishes as
+# restricted by default — first publish needs --access public.
+# Usage: is_scoped_package <dir>
+is_scoped_package() {
+  local dir="$1"
+  [[ -f "$dir/package.json" ]] || return 1
+  node -e '
+    const fs = require("fs");
+    const pkg = JSON.parse(fs.readFileSync(process.argv[1], "utf8"));
+    process.exit(typeof pkg.name === "string" && pkg.name.startsWith("@") ? 0 : 1);
+  ' "$dir/package.json"
+}
diff --git a/tests/workspaces.bats b/tests/workspaces.bats
new file mode 100644
index 0000000..ca28bcb
--- /dev/null
+++ b/tests/workspaces.bats
@@ -0,0 +1,117 @@
+#!/usr/bin/env bats
+
+setup() {
+  source "$BATS_TEST_DIRNAME/../scripts/workspaces.sh"
+
+  # Build a throwaway monorepo to exercise discovery against.
+  REPO="$(mktemp -d)"
+
+  mk_pkg() {
+    local dir="$1" json="$2"
+    mkdir -p "$REPO/$dir"
+    printf '%s' "$json" > "$REPO/$dir/package.json"
+  }
+}
+
+teardown() {
+  rm -rf "$REPO"
+}
+
+# ── read_workspace_patterns ──────────────────────────────────────
+
+@test "read_workspace_patterns: array form" {
+  mk_pkg "." '{"name":"root","workspaces":["packages/*","tools/cli"]}'
+  run read_workspace_patterns "$REPO/package.json"
+  [[ "${lines[0]}" == "packages/*" ]]
+  [[ "${lines[1]}" == "tools/cli" ]]
+}
+
+@test "read_workspace_patterns: object form" {
+  mk_pkg "." '{"name":"root","workspaces":{"packages":["libs/*"]}}'
+  run read_workspace_patterns "$REPO/package.json"
+  [[ "${lines[0]}" == "libs/*" ]]
+}
+
+@test "read_workspace_patterns: no workspaces field emits nothing" {
+  mk_pkg "." '{"name":"root"}'
+  run read_workspace_patterns "$REPO/package.json"
+  [[ -z "$output" ]]
+}
+
+@test "read_workspace_patterns: missing file emits nothing" {
+  run read_workspace_patterns "$REPO/does-not-exist.json"
+  [[ -z "$output" ]]
+}
+
+# ── discover_packages ────────────────────────────────────────────
+
+@test "discover_packages: expands a glob to each package dir" {
+  mk_pkg "." '{"name":"root","workspaces":["packages/*"]}'
+  mk_pkg "packages/a" '{"name":"a","version":"1.0.0"}'
+  mk_pkg "packages/b" '{"name":"b","version":"1.0.0"}'
+
+  run discover_packages "$REPO"
+  [[ "$output" == *"packages/a"* ]]
+  [[ "$output" == *"packages/b"* ]]
+  [[ "${#lines[@]}" -eq 2 ]]
+}
+
+@test "discover_packages: ignores glob matches without a package.json" {
+  mk_pkg "." '{"name":"root","workspaces":["packages/*"]}'
+  mk_pkg "packages/a" '{"name":"a","version":"1.0.0"}'
+  mkdir -p "$REPO/packages/not-a-pkg"
+
+  run discover_packages "$REPO"
+  [[ "$output" == *"packages/a"* ]]
+  [[ "$output" != *"not-a-pkg"* ]]
+  [[ "${#lines[@]}" -eq 1 ]]
+}
+
+@test "discover_packages: handles an explicit (non-glob) path" {
+  mk_pkg "." '{"name":"root","workspaces":["tools/cli"]}'
+  mk_pkg "tools/cli" '{"name":"cli","version":"1.0.0"}'
+
+  run discover_packages "$REPO"
+  [[ "$output" == *"tools/cli"* ]]
+  [[ "${#lines[@]}" -eq 1 ]]
+}
+
+@test "discover_packages: no workspaces field emits nothing" {
+  mk_pkg "." '{"name":"root","version":"1.0.0"}'
+  run discover_packages "$REPO"
+  [[ -z "$output" ]]
+}
+
+# ── is_private_package ───────────────────────────────────────────
+
+@test "is_private_package: true when private is set" {
+  mk_pkg "p" '{"name":"p","private":true}'
+  run is_private_package "$REPO/p"
+  [[ "$status" -eq 0 ]]
+}
+
+@test "is_private_package: false when private is absent" {
+  mk_pkg "p" '{"name":"p","version":"1.0.0"}'
+  run is_private_package "$REPO/p"
+  [[ "$status" -ne 0 ]]
+}
+
+@test "is_private_package: false when private is explicitly false" {
+  mk_pkg "p" '{"name":"p","private":false}'
+  run is_private_package "$REPO/p"
+  [[ "$status" -ne 0 ]]
+}
+
+# ── is_scoped_package ────────────────────────────────────────────
+
+@test "is_scoped_package: true for @scope/name" {
+  mk_pkg "p" '{"name":"@acme/widget","version":"1.0.0"}'
+  run is_scoped_package "$REPO/p"
+  [[ "$status" -eq 0 ]]
+}
+
+@test "is_scoped_package: false for an unscoped name" {
+  mk_pkg "p" '{"name":"widget","version":"1.0.0"}'
+  run is_scoped_package "$REPO/p"
+  [[ "$status" -ne 0 ]]
+}