Set theme

Use this action to set the theme Home Assistant uses by default, for light mode and, optionally, for dark mode. A common use is to switch themes automatically, for example a darker look in the evening and a lighter one during the day.

The theme you set here is saved and restored when Home Assistant restarts. If someone picks a theme manually on their user profile, that choice overrides this action for that person.

Using this action from the user interface

If you prefer building automations and scripts visually, Home Assistant walks you through this action step by step. You pick what to target, tweak a few options, and save. No YAML knowledge required.

To set the theme from an automation or a script:

1. Go to Settings > Automations & scenes.
2. Open an existing automation or script, or select Create automation > Create new automation.
3. If you’re setting up a new automation, add a trigger in the When section. Scripts don’t need a trigger. They run when something else calls them.
4. In the Then do section, select Add action.
5. Search for and select Set theme.
6. Select the Theme to use, and optionally a Dark theme override.
7. Select Save.

Options in the UI

Set at least one of Theme or Dark theme override. Any option you leave out keeps its previous value.

Using this action in YAML

If you work directly in YAML, or you want to know exactly what Home Assistant does under the hood, this section has the technical reference. It lists the field names you use in YAML, their types, and which ones are required.

In YAML, refer to this action as frontend.set_theme. A basic example looks like this:

action: frontend.set_theme
data:
  name: "default"

This sets the default light-mode theme back to the standard Home Assistant theme.

Options in YAML

You must set at least one of name or name_dark. Any option you leave out keeps its previous value.

Good to know

• The theme has to be installed and enabled before you can set it. See defining themes.
• Only administrators can run this action.
• A theme someone selects on their own user profile overrides this action for that person, across their devices.

Try it yourself

Ready to test this? Open Developer tools > Actions, search for this action, fill in the fields, and select Perform action. You see what happens on your actual entitiesAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more] without writing a line of YAML.

More examples

Real scenarios where this action shows up in automations and scripts. Copy any example and adapt it to your setup.

Automation: a dark theme at night, a light theme during the day

Switch to a darker theme at sunset and back to a lighter one at sunrise.

• Trigger: Sun: sunset, and Sun: sunrise
• Action: Set theme, picking the matching theme for each

alias: "Day and night theme"
triggers:
  - trigger: sun
    event: sunset
    id: "night"
  - trigger: sun
    event: sunrise
    id: "day"
actions:
  - choose:
      - conditions:
          - condition: trigger
            id: "night"
        sequence:
          - action: frontend.set_theme
            data:
              name: "HA Dark"
      - conditions:
          - condition: trigger
            id: "day"
        sequence:
          - action: frontend.set_theme
            data:
              name: "HA Light"

Automation: apply your preferred light and dark themes at startup

Set both a light-mode theme and a dark-mode override whenever Home Assistant starts, so every user and device falls back to your preferred look.

• Trigger: Home Assistant starts
• Action: Set theme, with both a theme and a dark theme override

alias: "Apply preferred themes on startup"
triggers:
  - trigger: homeassistant
    event: start
actions:
  - action: frontend.set_theme
    data:
      name: "HA Light"
      name_dark: "HA Dark"

Still stuck?

The Home Assistant community is quick to help: join Discord for real-time chat, post on the community forum with the action you’re calling and what you expected to happen, or share on our subreddit /r/homeassistant.

Related actions

These actions work well alongside this one:

• Reload themes: Reloads the theme configuration from your configuration.yaml file.