Can I customize checkout with my theme?
No, not through the theme. Checkout is a separate, Shopify-hosted system, Theme settings, Custom CSS, and theme code have no effect on it. checkout.liquid (the old way a theme could touch checkout) was retired in 2025; every store now uses Checkout Extensibility, a completely separate customization system from the theme editor.
What you can actually change
Settings → Checkout → open a checkout configuration to reach the checkout and accounts editor. It's a separate tool from the theme editor, and also covers the thank you, order status, and customer accounts pages.
- Every plan: branding (logo, colors, fonts, corner radii, spacing) and toggling basic form fields, all through that editor's Settings panel, no code involved.
- Shopify Plus only: app blocks and custom checkout logic, built with Shopify Functions and UI Extensions and installed as an app, not written as theme code. This is genuine custom development (Shopify CLI, not Liquid), not something a theme purchase includes.
Info
Shopify's guides: using the checkout and accounts editor, customizing checkout style, and customizing checkout with apps (Plus).
Why themes can't touch it
Checkout handles payment and PCI compliance. Shopify keeps it on locked-down, audited code so every store's checkout stays secure and fast, regardless of what theme or apps that store runs. That's also why "Checkout is unchanged" shows up as a caveat throughout these guides, colors, buttons, custom CSS, none of it reaches checkout, on purpose.
Troubleshooting
- My theme's colors don't match on checkout: expected, set them separately in the checkout and accounts editor's branding settings.
- An app changed my checkout but not the theme: that's a checkout app or Shopify Function, a different system from theme app embeds.
- I'm on Shopify Plus and want custom checkout fields or logic: that's Checkout Extensibility development (Functions/UI Extensions). Talk to a Shopify Plus partner or developer, it's outside theme customization entirely.