GA4 linking is the connection between a Google Ads account and a Google Analytics 4 property. Once the two are linked, Google Ads costs, clicks and campaign names appear in GA4 reports, and you can bring GA4 key events and audiences into Google Ads to use for bidding and targeting.
How GA4 linking works
You create the link from the Admin area of GA4, under product links, or from the data manager in Google Ads. You need the Editor role on the GA4 property and administrative access to the Google Ads account. A single GA4 property can link to several Google Ads accounts, and linking a manager account covers the accounts beneath it.
During setup you choose two things. Personalised advertising decides whether GA4 audiences can be shared with Google Ads for remarketing. Auto-tagging, if it is not already on, needs enabling, because GA4 relies on the click ID from auto-tagging to tie each visit back to the campaign, ad group and keyword.
After linking, three things become possible. GA4 shows Google Ads campaigns with their costs in its advertising and acquisition reports. Google Ads can import GA4 key events as conversion actions. And GA4 audiences, such as people who viewed a pricing page but did not enquire, become available in Google Ads for targeting or bidding signals. You can also show GA4 engagement metrics as columns in Google Ads.
Why it matters
Without the link, paid traffic in GA4 is hard to read. You cannot see how visitors from a particular campaign behave on the site, and you end up relying on the numbers each ad platform reports about itself. With it, you can compare paid visitors with organic visitors to the same page and spot campaigns that bring traffic but no engagement.
For UK sites, consent shapes what the link can do. Visitors who decline analytics or advertising cookies under PECR will not be fully measured, and audiences can only be built from people who agreed. With consent mode in place, Google models part of the gap, so expect GA4 and Google Ads figures to differ.
Common mistakes
- Importing a GA4 key event as a primary conversion while a Google Ads tag already counts the same action, so every enquiry is counted twice.
- Linking a test or duplicate GA4 property instead of the one the site actually sends data to.
- Turning auto-tagging off, which breaks the campaign detail in GA4.
- Leaving personalised advertising off and then wondering why GA4 audiences do not appear in Google Ads.
- Expecting the two tools to agree exactly, even though they attribute and date conversions differently.
How to act on it
Check GA4 Admin to see whether a link exists and which Google Ads account it points to. Confirm auto-tagging is on. Then decide, for each conversion, which tool is the source of truth, and make only that version a primary conversion in Google Ads. Set any duplicates to secondary so they are reported but not used for bidding.
A day or two after linking, check that Google Ads cost data appears in GA4. If your site uses a cookie banner, test with consent both accepted and declined, and confirm paid visits still show in GA4, in reduced form, when it is declined. I set up and audit this link as part of Google Ads management, because a double-counted conversion quietly teaches Smart Bidding to overspend.