Definition
SEO migration is the technical and strategic process of making major changes to a website (domain change, CMS change, URL structure change, HTTPS migration, site merger, or complete redesign) while preserving as much organic search rankings and traffic as possible. A poorly managed SEO migration can result in a 20 to 80% loss of organic traffic, sometimes irreversibly. Critical steps include: complete inventory of all indexed URLs, 301 redirect mapping (old URL to new URL), preserving canonical tags, hreflang, and meta tags, transferring the backlink profile (updating links where possible), submitting the new sitemap to Google Search Console, intensive post-migration monitoring (traffic, indexation, rankings, 404 errors), and preserving structured data.
Key Points
- Critical process that can cause 20-80% traffic loss if poorly managed
- Exhaustive 301 redirect mapping is essential
- Intensive post-migration monitoring for at least 3 months
Practical Examples
Domain migration
When switching from old-domain.com to new-domain.com, create a complete mapping of 500 indexed URLs with their respective 301 redirects. Update the address in Google Search Console and monitor indexation daily for 3 months.
CMS migration
During a WordPress to Shopify migration, identify URL structure changes (/blog/article to /blogs/news/article) and implement 301 redirects. Test each redirect before going live.
Frequently Asked Questions
With a well-executed migration, traffic typically stabilizes in 2 to 6 months. Initial losses of 10-20% are normal in the first few weeks. If the loss exceeds 30% after 3 months, there are likely errors in redirects or technical configuration.
Yes, ideally every indexed URL should have a 301 redirect to its equivalent on the new site. For large sites, prioritize pages generating traffic and having backlinks. Never redirect all pages to the homepage, as this would be treated as a soft 404.
Go Further with LemmiLink
Discover how LemmiLink can help you put these SEO concepts into practice.
Last updated: 2026-02-07