Website Migration SEO: What Actually Changes After Launch

Every website project ends the same way. The new site goes live, everyone agrees it looks better than the old one, and then the invoice lands. Six weeks later the only question anyone actually cares about is whether anything has changed in the numbers.

Website migration SEO is the part of the work that decides the answer. It is unglamorous, it happens mostly before launch, and it is the reason two sites that look equally good can perform completely differently.

Here is what we did on a recent migration for a UK technical ceramics manufacturer, and what the data looked like six weeks afterwards. We have kept the client anonymous, but the numbers are their real Google Search Console figures.

The problem was not how the old site looked

The business had grown by acquisition and was trading under one name while its website sat on a completely different domain. The practical effect was simple. Someone who had met them at a trade show, or been given their name by a colleague, typed that name into Google and struggled to find them. A business whose own customers can’t find it by name is losing enquiries before search rankings even enter the conversation.

The second problem was harder to see. The old site described the products the way the business talked about them internally, not the way buyers searched for them. Page titles and headings carried very little of the language customers actually used. Google indexed the site, but there was almost nothing on it that matched a real purchase-intent search.

What website migration SEO actually involves

Three things did most of the work.

A redirect map built from the old site’s full history. We pulled every URL the old domains had ever had, including pages that were no longer in the navigation, and mapped each one to its closest equivalent on the new site. This matters more than it sounds. Google’s guidance is to use a permanent server-side redirect for each page to its equivalent page on the new site, not a blanket redirect to the homepage. Google has also said redirects should stay in place for at least a year, because its systems need to see the change several times before recording it. A migration that redirects everything to the homepage throws away years of accumulated signals in a single afternoon.

Search Console groundwork. Where a site moves domain, Google’s Change of Address tool forwards signals from the old property to the new one, but it only works if you own both properties and the redirects are already in place. This is a ten-minute job that is routinely skipped.

Page titles and headings rewritten around real searches. Every page title, meta description and H1 was rewritten around terms buyers actually type, checked against search volume data rather than assumed. Materials and product families each got their own page, so there was something specific for Google to rank rather than one catch-all products page.

Built for machines as well as people

The old site had no structured data, which is the markup that tells search engines and AI assistants what a page is about rather than leaving them to guess from the text see our guide to structured data. The new one has it throughout.

We also publish an llms.txt file, and we will be straight about that one: Google has said publicly that it does not use llms.txt and has no plans to, and a 2026 study of 300,000 domains found roughly 10% adoption with no clear effect on how often a site is cited by AI tools. Claude and Perplexity do fetch it. It costs almost nothing to publish, so we ship it, but anyone selling it to you as an AI visibility strategy is selling you a file, not a result. The work that actually made this site legible to AI tools was clean page structure, specific product and material pages, and schema.

Within the first month the new site received its first visits from ChatGPT and Claude. The old site had never had any. In absolute terms this is a small channel, around 0.3% of visits for a typical site, and it would be silly to build a business case on it today. What makes it worth tracking is the quality: one study of 97 B2B lead generation websites found visitors arriving from ChatGPT converted into enquiries at 2.1%, against 0.5% from Google search.

What changed in six weeks

The detail behind the headline numbers matters more than the percentages. Nine of the ten keywords now bringing in the most visibility did not appear in Google at all before launch. The site is not ranking better for the terms it used to rank for. It is appearing for product searches it was completely absent from, which is a different and more useful thing.

Traffic is not the point, enquiries are

Before the migration this business received around four enquiries a month. In the first six weeks after launch it received sixteen contact form submissions, several of them direct quote requests, and they came from product and material pages rather than only the contact page. The new site is doing the selling before the buyer reaches the form see why more traffic doesn’t always mean more enquiries.

One honest note on attribution: a portion of that traffic arrives with no traceable source, partly because of redirects from the old domain, so the true split between search-driven and direct enquiries is less tidy than any report will show you.

What we would not promise

The build took ten weeks, not the six we scoped, because the technical content needed checking properly and we were not prepared to publish material specifications we weren’t sure about. The site launched in the middle of summer, which is the worst time of year for this industry’s enquiry levels, and it still outperformed the baseline. That was a surprise, not a plan.

Six weeks of data is early. Rankings move, competitors respond, and some of these positions will drift before they settle. This client is on a twelve-month plan precisely because a migration is a starting point, not a finished job. Anyone promising you a fixed percentage uplift before they have seen your redirect map is guessing.

If you are planning a migration, ask these questions

Ask your agency how they will build the redirect map and whether it covers historical URLs, not just current ones. Ask how long redirects will stay in place. Ask what happens to your page titles and whether anyone is checking them against real search data. Ask what the current numbers are, before anything changes.

That last one is the important one. Most migrations can’t be judged afterwards because nobody wrote down what “before” looked like. If you are weighing up a rebuild, our website health check gives you that baseline, whoever ends up doing the work.

Frequently Asked Questions

How long does it take to see results after a website migration?

Expect several weeks of movement before anything settles. Search engines need to crawl the new URLs, follow the redirects and re-evaluate the pages, and Google has said it needs to see a redirect more than once before it records the change. In the example above, meaningful growth appeared within two to three weeks and was still climbing at six weeks, but a fair judgement needs three to six months.

Will I lose my Google rankings when I move to a new domain?

Not if the migration is done properly. The risk comes from lost or lazy redirects, not from moving itself. Permanent server-side redirects from each old page to its closest equivalent, kept in place for at least a year, are what protect the rankings you already have.

Does my domain need to match my business name?

It is not a ranking factor, but it is a findability one. If customers who already know your name type it into Google and can’t work out which result is you, you are losing enquiries that cost you nothing to win. Consolidating onto the domain that matches your trading name removes that friction.

What is the most common website migration SEO mistake?

Redirecting every old page to the new homepage. It is quick, it avoids visible 404 errors, and it wastes the value of every individual page you had built up. Mapping each URL to its closest equivalent is slower and is the difference between keeping your visibility and starting again.

Will a new website help me show up in ChatGPT and other AI assistants?

It can, but not because of any single file or trick. Clear page structure, specific pages for specific products or services, and structured data are what make a site easy for AI tools to read and cite. Google has confirmed it does not use llms.txt, so treat any pitch built around it with caution.

How do I know whether my migration actually worked?

Record your baseline before anything changes: clicks and impressions in Google Search Console, the number of search terms you appear for, and your monthly enquiry count. Compare equal periods either side of launch rather than comparing this month to last month, which mixes in seasonality. Enquiries are the number that matters most.