Schema markup implementation for technical SEO involves adding structured data to a website's HTML code to provide search engines with additional context about the content on the page. Schema markup uses a standardized format, such as JSON-LD or microdata, to mark up specific elements and attributes on a webpage. By implementing schema markup, websites can enhance their visibility in search engine results and improve the understanding of their content by search engines. This can lead to the display of rich snippets, which provide more detailed and visually appealing search results, ultimately improving click-through rates and overall SEO performance.