Converting a design from Figma to HTML for WordPress and Shopify involves transforming visual elements into functional web pages. For WordPress, the HTML is adapted into a theme with custom functionalities, while Shopify integration involves creating a theme using Liquid templating. Key steps include responsive design, cross-browser testing, and optimizing for SEO and performance. The process ensures a seamless transition from design to live website, with documentation for customization options and attention to platform-specific features for WordPress and Shopify.