A well-planned redesign shouldn’t hurt your rankings, but a poorly planned one will devastate them. To protect SEO: set up 301 redirects from old URLs to new ones, preserve your content (don’t delete pages), maintain your keyword targeting strategy, implement proper on-page SEO elements, keep your site structure logical, don’t change domain names unless necessary, submit your new sitemap to Google Search Console. Work with an SEO professional to ensure your redesign protects your rankings.