diff --git a/docker/ha-addon-rootfs/etc/cont-init.d/30-esphome-fork.sh b/docker/ha-addon-rootfs/etc/cont-init.d/30-esphome-fork.sh
new file mode 100755
index 0000000000..03dbb34c8f
--- /dev/null
+++ b/docker/ha-addon-rootfs/etc/cont-init.d/30-esphome-fork.sh
@@ -0,0 +1,47 @@
+#!/usr/bin/with-contenv bashio
+# ==============================================================================
+# This file installs the user ESPHome fork if specified.
+# The fork must be up to date with the latest ESPHome dev branch
+# and have no conflicts.
+# This config option only exists in the ESPHome Dev add-on.
+# ==============================================================================
+
+declare esphome_fork
+
+if bashio::config.has_value 'esphome_fork'; then
+  esphome_fork=$(bashio::config 'esphome_fork')
+  # format: [username][/repository]:ref
+  if [[ "$esphome_fork" =~ ^(([^/]+)(/([^:]+))?:)?([^:/]+)$ ]]; then
+    username="${BASH_REMATCH[2]:-esphome}"
+    repository="${BASH_REMATCH[4]:-esphome}"
+    ref="${BASH_REMATCH[5]}"
+  else
+    bashio::exit.nok "Invalid esphome_fork format: $esphome_fork"
+  fi
+  full_url="https://github.com/${username}/${repository}/archive/${ref}.tar.gz"
+  bashio::log.info "Checking forked ESPHome"
+  dev_version=$(python3 -c "from esphome.const import __version__; print(__version__)")
+  bashio::log.info "Downloading ESPHome from fork '${esphome_fork}' (${full_url})..."
+  curl -L -o /tmp/esphome.tar.gz "${full_url}" -qq ||
+    bashio::exit.nok "Failed downloading ESPHome fork."
+  bashio::log.info "Installing ESPHome from fork '${esphome_fork}' (${full_url})..."
+  rm -rf /esphome || bashio::exit.nok "Failed to remove ESPHome."
+  mkdir /esphome
+  tar -zxf /tmp/esphome.tar.gz -C /esphome --strip-components=1 ||
+    bashio::exit.nok "Failed installing ESPHome from fork."
+  pip install -U -e /esphome || bashio::exit.nok "Failed installing ESPHome from fork."
+  rm -f /tmp/esphome.tar.gz
+  fork_version=$(python3 -c "from esphome.const import __version__; print(__version__)")
+
+  if [[ "$fork_version" != "$dev_version" ]]; then
+    bashio::log.error "############################"
+    bashio::log.error "Uninstalled fork as version does not match"
+    bashio::log.error "Update (or ask the author to update) the branch"
+    bashio::log.error "This is important as the dev addon and the dev ESPHome"
+    bashio::log.error "branch can have changes that are not compatible with old forks"
+    bashio::log.error "and get reported as bugs which we cannot solve easily."
+    bashio::log.error "############################"
+    bashio::exit.nok
+  fi
+  bashio::log.info "Installed ESPHome from fork '${esphome_fork}' (${full_url})..."
+fi