Migrating a WordPress site to the Jamstack involves setting up a new Gatsby site, installing necessary plugins like WPGraphQL and WPGraphiQL, creating pages from WordPress data using GraphQL queries, adding a shared layout and styles, creating pages from WordPress posts, using WordPress settings to configure the Gatsby site, deploying the site to Netlify using the Netlify CLI, and automatically triggering deploys whenever changes are made in WordPress. The process involves several key steps, including setting up a new Gatsby site, installing necessary plugins, querying for WordPress data using GraphQL, creating pages from that data, adding styles and layouts, deploying the site to Netlify, and configuring WordPress settings to trigger automatic deploys when content is updated. With these steps, developers can create a fully functional Jamstack frontend for their WordPress sites, automating the rebuild process whenever code or content changes.