diff --git a/.github/workflows/ember-version-enforcement.yml b/.github/workflows/ember-version-enforcement.yml
new file mode 100644
index 00000000000..886a491a51b
--- /dev/null
+++ b/.github/workflows/ember-version-enforcement.yml
@@ -0,0 +1,57 @@
+# This workflow is designed to stop us accidently committing the lockfile/packagejson symlink changes
+# which would cause the default Ember version to change.
+
+name: Ember Version Enforcement
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+permissions:
+  contents: write
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ github.head_ref }}
+      - name: Setup Node
+        uses: actions/setup-node@v3
+        with:
+          node-version: 20
+          cache: yarn
+      - name: Yarn install
+        run: |
+          cd app/assets/javascripts/discourse
+          yarn install
+      - name: "Check default ember version"
+        working-directory: app/assets/javascripts/discourse
+        run: |
+          node -e '
+            const version = require("ember-source/package.json").version;
+            console.log("Ember version is", version);
+            if(version.split(".")[0] !== "3"){
+              console.log(`Ember has unexpectedly been upgraded to version ${version}. If this is intentional, remove this github workflow.`);
+              process.exit(1);
+            }
+          '
+      - name: Upgrade ember
+        run: |
+          script/switch_ember_version 5
+          cd app/assets/javascripts/discourse
+          yarn install
+      - name: "Check upgraded version"
+        working-directory: app/assets/javascripts/discourse
+        run: |
+          node -e '
+            const version = require("ember-source/package.json").version;
+            console.log("Ember version is", version);
+            if(version.split(".")[0] !== "5"){
+              console.log(`Expected Ember 5, but found ${version}`);
+              process.exit(1);
+            }
+          '
diff --git a/.github/workflows/ember-version-lockfiles.yml b/.github/workflows/ember-version-lockfiles.yml
new file mode 100644
index 00000000000..7e0bbb48c4a
--- /dev/null
+++ b/.github/workflows/ember-version-lockfiles.yml
@@ -0,0 +1,38 @@
+# This workflow will run on dependabot pull requests to ensure that they update both the ember3 and ember5 lockfiles
+
+name: Ember Version Lockfiles
+
+on:
+  - pull_request
+
+permissions:
+  contents: write
+
+jobs:
+  help_dependabot:
+    runs-on: ubuntu-latest
+    if: ${{ github.actor == 'dependabot[bot]' }}
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ github.head_ref }}
+      - name: Move lockfile to correct location
+        run: |
+          # Dependabot gets confused by the symlinks and dumps the updated lockfile in the root of the repo.
+          # Let's move it back to the correct location.
+          if [[ -f yarn-ember3.lock ]]; then
+            mv yarn-ember3.lock app/assets/javascripts/yarn-ember3.lock
+          fi
+      - name: Update ember5 lockfile
+        run: script/regen_ember_5_lockfile
+      - name: Push changes
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          if [ ! -z "$(git status --porcelain)" ]; then
+            git config --global user.email "build@discourse.org"
+            git config --global user.name "discoursebuild"
+            git add .
+            git commit -m "Update lockfiles for ember version flag"
+            git push
+          fi
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 0bf9d527439..8d1adcbc825 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -295,7 +295,7 @@ jobs:
 
   core_frontend_tests:
     if: github.event_name == 'pull_request' || github.repository != 'discourse/discourse-private-mirror'
-    name: core frontend (${{ matrix.browser }})
+    name: core frontend (${{ matrix.browser }})${{ matrix.updated_ember && ' (Ember 5)' || '' }}
     runs-on: ubuntu-20.04-8core
     container:
       image: discourse/discourse_test:slim-browsers
@@ -307,6 +307,10 @@ jobs:
       fail-fast: false
       matrix:
         browser: ["Chrome", "Firefox ESR", "Firefox Evergreen"]
+        updated_ember: [false]
+        include:
+          - browser: Chrome
+            updated_ember: true
 
     env:
       TESTEM_BROWSER: ${{ (startsWith(matrix.browser, 'Firefox') && 'Firefox') || matrix.browser }}
@@ -333,6 +337,10 @@ jobs:
           path: ${{ steps.yarn-cache-dir.outputs.dir }}
           key: ${{ runner.os }}-yarn-${{ hashFiles('**/yarn.lock') }}-cachev2
 
+      - name: Upgrade Ember
+        if: matrix.updated_ember == true
+        run: script/switch_ember_version 5
+
       - name: Yarn install
         working-directory: ./app/assets/javascripts/discourse
         run: yarn install --frozen-lockfile
diff --git a/app/assets/javascripts/package-ember5.json b/app/assets/javascripts/package-ember5.json
new file mode 100644
index 00000000000..c02b40db7b2
--- /dev/null
+++ b/app/assets/javascripts/package-ember5.json
@@ -0,0 +1,35 @@
+{
+  "private": true,
+  "scripts": {
+    "postinstall": "./run-patch-package"
+  },
+  "workspaces": [
+    "admin",
+    "bootstrap-json",
+    "deprecation-silencer",
+    "dialog-holder",
+    "discourse",
+    "discourse-common",
+    "discourse-hbr",
+    "discourse-i18n",
+    "discourse-markdown-it",
+    "discourse-plugins",
+    "discourse-widget-hbs",
+    "ember-cli-progress-ci",
+    "ember-production-deprecations",
+    "float-kit",
+    "pretty-text",
+    "select-kit",
+    "theme-transpiler",
+    "truth-helpers",
+    "wizard"
+  ],
+  "resolutions": {
+    "**/unset-value": "2.0.1",
+    "**/ember-source": "5.4.0"
+  },
+  "devDependencies": {
+    "patch-package": "^8.0.0",
+    "postinstall-postinstall": "^2.1.0"
+  }
+}
diff --git a/app/assets/javascripts/package.json b/app/assets/javascripts/package.json
new file mode 120000
index 00000000000..8be34de0780
--- /dev/null
+++ b/app/assets/javascripts/package.json
@@ -0,0 +1 @@
+package-ember3.json
\ No newline at end of file
diff --git a/app/assets/javascripts/yarn.lock b/app/assets/javascripts/yarn.lock
new file mode 120000
index 00000000000..dc5a2ab4567
--- /dev/null
+++ b/app/assets/javascripts/yarn.lock
@@ -0,0 +1 @@
+yarn-ember3.lock
\ No newline at end of file
diff --git a/bin/ember-cli b/bin/ember-cli
index ee9e46ea0be..c0d78350f01 100755
--- a/bin/ember-cli
+++ b/bin/ember-cli
@@ -56,6 +56,17 @@ if !args.include?("test") && !args.include?("build") && !args.include?("--proxy"
   args << PROXY
 end
 
+if !["3", "5", nil].include?(ENV["EMBER_VERSION"])
+  raise "Unknown ember version #{ENV["EMBER_VERSION"]}"
+end
+
+system(
+  "script/switch_ember_version",
+  ENV["EMBER_VERSION"] || "3",
+  exception: true,
+  chdir: RAILS_ROOT,
+)
+
 # Running yarn install in the root directory will also run it for YARN_DIR via a post-install hook
 exit 1 if !system "yarn", "-s", "install", "--cwd", RAILS_ROOT
 
diff --git a/lib/tasks/assets.rake b/lib/tasks/assets.rake
index d08d707c0dd..09950f71f7e 100644
--- a/lib/tasks/assets.rake
+++ b/lib/tasks/assets.rake
@@ -8,6 +8,16 @@ end
 
 task "assets:precompile:build" do
   if ENV["SKIP_EMBER_CLI_COMPILE"] != "1"
+    ember_version = ENV["EMBER_VERSION"] || "3"
+
+    raise "Unknown ember version '#{ember_version}'" if !%w[3 5].include?(ember_version)
+
+    if ENV["EMBER_VERSION"] == "5"
+      puts "Upgrading to Ember 5..."
+      system("script/switch_ember_version", ember_version, exception: true, chdir: Rails.root)
+      system("yarn install", exception: true, chdir: "app/assets/javascripts/discourse")
+    end
+
     compile_command = "yarn --cwd app/assets/javascripts/discourse run ember build"
 
     heap_size_limit = check_node_heap_size_limit
diff --git a/script/regen_ember_5_lockfile b/script/regen_ember_5_lockfile
new file mode 100755
index 00000000000..76e6d9483b7
--- /dev/null
+++ b/script/regen_ember_5_lockfile
@@ -0,0 +1,21 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require "fileutils"
+
+# rubocop:disable Discourse/NoChdir
+Dir.chdir("#{__dir__}/../app/assets/javascripts") do
+  FileUtils.mv("yarn.lock", "yarn.lock-tmp")
+  FileUtils.mv("package.json", "package.json-tmp")
+
+  File.symlink("package-ember5.json", "package.json")
+  File.symlink("yarn-ember5.lock", "yarn.lock")
+
+  system "yarn install", exception: true
+
+  FileUtils.rm("yarn-ember5.lock")
+  FileUtils.cp("yarn-ember3.lock", "yarn-ember5.lock")
+
+  FileUtils.mv("yarn.lock-tmp", "yarn.lock")
+  FileUtils.mv("package.json-tmp", "package.json")
+end
diff --git a/script/switch_ember_version b/script/switch_ember_version
new file mode 100755
index 00000000000..566db38b523
--- /dev/null
+++ b/script/switch_ember_version
@@ -0,0 +1,17 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require "fileutils"
+
+v = ARGV[0]
+
+raise "Unexpected version #{v}" if !%w[3 5].include?(v)
+
+# rubocop:disable Discourse/NoChdir
+Dir.chdir("#{__dir__}/../app/assets/javascripts") do
+  FileUtils.rm("package.json")
+  FileUtils.rm("yarn.lock")
+
+  File.symlink("package-ember#{v}.json", "package.json")
+  File.symlink("yarn-ember#{v}.lock", "yarn.lock")
+end