GA4 AI Assistant Channel

The AI Assistant channel is a default channel in Google Analytics 4 that groups sessions referred by recognized AI assistants. When GA4 matches a visit's referrer to its list of AI assistants, it sets the medium to 'ai-assistant' and the campaign to '(ai-assistant)', and the session shows up under AI Assistant instead of Referral. No setup is needed.

Google added the channel on May 13, 2026, and it reached most properties by early June. Until then, AI-referred traffic sat in Referral unless a team built its own custom channel group, which Google had documented in August 2025. The launch announcement named ChatGPT, Gemini and Claude as examples. Google's default channel group definitions now describe AI Assistant as traffic 'from sources like ChatGPT, Gemini, Deepseek, Copilot, or Grok', and Google has not published the full list of recognized referrers.

The same definitions page draws one line clearly: the channel excludes Google's own AI Overviews and AI Mode. Clicks from those features stay in Organic Search, mixed with regular Google results. To see Google's AI visibility you need Search Console's generative AI performance report, which reports impressions but not clicks.

Several other gaps mean the channel undercounts AI influence:

• Referrer-less visits from AI mobile apps, in-app browsers and copied links land in Direct, a large part of AI dark traffic.
• Assistants that are not on Google's list stay in Referral. Search Engine Journal reported in July 2026 that Perplexity traffic was still landing there.
• A single source can split three ways. The same report found chatgpt.com sessions spread across AI Assistant, Referral and Unassigned, the last when the medium arrives as '(not set)'.
• Default channel groups cannot be edited, and the classification only applies from each property's rollout date, so year-over-year growth in the channel partly reflects the switch itself.

The common fix is a custom channel group with a rule on session source (a regex of AI domains such as chatgpt.com, perplexity, gemini.google.com, copilot.microsoft.com and claude.ai), ordered above Referral and Organic Search so it claims those sessions first. Custom channel groups also apply to historical data, which restores a consistent trend line. Avoid bare tokens such as 'gpt' or 'google' that match unrelated sources.

Even a well-built channel only counts visits that carry a readable source. Many people read a recommendation in ChatGPT and then type the brand or search for it, which no channel rule can catch. That is why teams combine the channel with self-reported attribution, branded search trends and zero-click attribution estimates, and report AI visibility separately from AI traffic in their AI search analytics.