Criteo yesterday published an update on its integration with OpenAI's advertising pilot inside ChatGPT, disclosing that more than one thousand brands are now running active campaigns through its API connection - a milestone that marks a rapid scaling of a partnership that only formally launched on March 2, 2026. The update, released on May 5, 2026, also presents strengthened performance data showing AI-referred conversion rates approaching twice those of traditional search in several retail categories, a significant step up from the 1.5x figure the company first reported in March.

The numbers carry weight at a moment when the ChatGPT advertising ecosystem is expanding on multiple fronts. OpenAI today opened its self-serve Ads Manager to all US businesses, introducing cost-per-click bidding alongside the existing CPM model and publishing a Conversions API for post-click measurement. Criteo's update arrives in parallel, placing the company's early-mover position in sharper relief.

Early traction and the 1,000-brand threshold

According to Criteo's press release published May 5, 2026, the one thousand brands now live span both existing Criteo clients and advertisers new to the platform. That breadth is notable. It suggests the ChatGPT integration is drawing incremental participants rather than simply redistributing spend from Criteo's existing customer base - a point the company makes explicitly, characterizing budgets as additive rather than reallocated from other channels.

The agency dimension is also prominent in the update. According to the release, both holding companies and independent agencies are using the integration to test conversational AI within existing media planning and activation workflows. Tinuiti, one of the named participants, described the integration through Michelle Merklin, VP of Paid Search Innovation and Growth: "Tinuiti has been thrilled to deepen our partnership with Criteo through their pioneering ChatGPT ad integration. As early adopters of this technology, we've seen immediate interest from clients eager to explore the intersection of generative AI and commerce."

That agency engagement matters structurally. Holding companies and independent shops serve as distribution multipliers - their adoption accelerates access for brands that would not otherwise have direct relationships with OpenAI's sales team.

Conversion rate data: a strengthening signal

The performance metrics in today's update are the most closely watched element. When Criteo first disclosed its ChatGPT integration in March, it reported that users referred from LLM platforms like ChatGPT were converting at approximately 1.5 times the rate of other referral channels, based on a sample of 500 US retailers observed in February 2026. PPC Land covered that initial figure in its March 2 report on the partnership announcement, noting the methodology limitations of a single-month sample from a subset of the advertiser base.

Today's update moves that figure materially higher. According to the May 5 release, specific retail categories - consumer electronics, lifestyle and wellbeing, and home and garden - are now seeing close to two times higher conversion from AI-referred traffic compared with traditional search. The company attributes this to the nature of purchases in those categories: complex, discovery-driven decisions where shoppers arrive at ChatGPT already deep in a consideration process rather than at the beginning of a casual browse.

On top of conversion rate improvements, the update reports click-through rates roughly three times higher than comparable formats in other environments. That CTR figure, if sustained, would represent a meaningful engagement differential - one that could justify the premium CPM pricing that has characterized ChatGPT advertising since its February 9, 2026 launch. As PPC Land reported in April, CPMs on ChatGPT have fallen from $60 at launch to as low as $25, which makes the CTR advantage an increasingly important part of the performance case.

The caveat worth holding onto is the same one that applied to the earlier data. These figures come from Criteo's own reporting on its own client base. Independent, third-party verification of conversion performance at scale remains unavailable. Adthena's analysis of more than 29 million queries, published in early April, offered one of the few external data points on ChatGPT ad performance, but did not provide equivalent conversion rate benchmarks.

International expansion and access for smaller advertisers

The geographic footprint of the Criteo-OpenAI partnership has widened since March. According to the May 5 update, as ChatGPT Ads expands to multiple markets including Australia, Canada, and New Zealand, Criteo users gain the ability to activate campaigns in those international markets through the same integration. OpenAI's announcement on March 26 had flagged the international expansion alongside the disclosure that the ChatGPT ad pilot had crossed $100 million in annualized revenue within six weeks of launch.

For small and mid-sized businesses, Criteo is extending access through its Criteo GO platform, integrating ChatGPT as part of what the company describes as a self-service, cross-channel performance platform. Criteo expanded GO with full self-service access on March 31, 2026, opening AI-powered, cross-channel performance advertising to businesses that do not have managed service agreements. The ChatGPT integration now sits inside that infrastructure, meaning an SMB can in theory access conversational AI inventory through the same interface used to run display or retail media campaigns.

That structural change matters for the market. Before the GO expansion and the ChatGPT integration, accessing OpenAI's ad platform required either a direct relationship with OpenAI's sales team or sufficient budget to meet six-figure minimums. PPC Land noted in its coverage of the self-serve Ads Manager launch that the entry point had come down from $250,000 to $50,000. Criteo's GO integration opens a parallel path for advertisers whose budgets fall below that threshold.

What brands and agencies are reporting

The update includes five client and agency quotes, which offer a window into how participants are framing the pilot internally. Foot Locker Asia Pacific's Digital Marketing Director, Laura Cobertera, described ChatGPT as "a new way to show up for our customers earlier in their decision-making journey." HP's Global Head of Channel eCommerce, Colleen Gomez, characterized the integration as "unlocking a new opportunity that hasn't previously been accessible" and described it as a "test-and-learn foundation" to understand how the channel can complement traditional search.

Petbarn's Senior Performance Manager, Ben Zieschang, emphasized the discovery dimension - connecting with pet owners "while they're actively researching what's best for their pet." WITHIN Agency founder and CEO Joe Yakuel offered a more measured perspective, noting the integration gives an early opportunity to "understand how to engage consumers in these environments while balancing performance across channels."

The framing across these quotes is consistent: an exploratory posture, with emphasis on understanding a new channel rather than committing to it at scale. That tone reflects where the pilot actually sits. Attribution infrastructure on ChatGPT remains underdeveloped relative to established platforms. As PPC Land reported following the $100 million revenue milestone, ChatGPT still lacks the impression-level measurement and outcome tracking that performance marketers expect. Criteo's infrastructure adds some of that capability, but gaps remain substantial compared to what advertisers can measure on Google or Meta.

Three forward priorities

Criteo's update outlines three areas of focus as the pilot continues. The first is keeping the user experience central - ensuring ads in ChatGPT are relevant and aligned with how users explore and make decisions, increasingly informed by the company's commerce intelligence layer. The second is making AI-native media additive for marketers, integrating emerging environments into Criteo's cross-channel platform and expanding access through GO. The third is continuing to learn and scale responsibly, working with OpenAI to test formats, inform roadmap priorities, and use early results to shape outcome measurement.

That third priority points to the structural work still underway. Outcome measurement on conversational AI is genuinely different from established digital advertising environments. The shopper journey through ChatGPT - from discovery to product recommendation to click to purchase - involves more steps and less instrumentation than a comparable path through paid search. Criteo's commerce data infrastructure, which draws on 720 million daily shoppers and $1 trillion in annual transactions according to the company's February 2026 agentic commerce announcement, positions it as a candidate to help fill that measurement gap - but that work is ongoing.

Context: where the ChatGPT ad market stands

The Criteo update lands at a specific moment in the development of OpenAI's advertising business. The pilot formally launched on February 9, 2026, at a CPM of $60 with a minimum advertiser commitment of $200,000 to $250,000. Within six weeks it had crossed $100 million in annualized revenue, with more than 600 advertisers in the program. By mid-April, CPMs had fallen to as low as $25 and the minimum spend threshold had been cut to $50,000. Today's self-serve Ads Manager opening removes the minimum threshold for US advertisers entirely and introduces CPC bidding.

Against that backdrop, Criteo's position as the first and - until recently - most prominent ad tech integration partner takes on added significance. The company handles more than $4 billion in annual media spend across roughly 17,000 advertisers globally. Its commerce data, built from transactions across thousands of retailers, gives it a signal advantage in targeting and relevance that OpenAI's own infrastructure does not yet replicate. The combination of distribution scale and commerce intelligence was, according to Criteo's own account, the reason it was selected as the first integration partner in March.

The marketing industry is watching this channel carefully, and the data points it has been given so far are directionally consistent: high-intent users, elevated conversion rates in discovery-driven categories, CTRs above comparable formats elsewhere. Whether those signals hold at the scale of a mature advertising market - with broader advertiser participation, more diverse creative formats, and greater measurement transparency - remains the central open question.

Timeline

Summary

Who: Criteo (NASDAQ: CRTO), the Paris-headquartered advertising technology company activating more than $4 billion in annual media spend across approximately 17,000 advertisers globally, alongside OpenAI and participating brands and agencies including Foot Locker Asia Pacific, HP, Petbarn, Tinuiti, and WITHIN Agency.

What: Criteo today published a progress update on its integration with OpenAI's ChatGPT advertising pilot, disclosing that over 1,000 brands are now running campaigns through its API integration. Updated performance data shows AI-referred conversion rates approaching 2x those of traditional search in consumer electronics, lifestyle and wellbeing, and home and garden categories, and CTRs approximately 3x those of comparable formats in other environments. The integration has expanded to international markets including Australia, Canada, and New Zealand, and ChatGPT is now available to small and mid-sized businesses through Criteo GO.

When: The update was published on May 5, 2026. The Criteo-OpenAI partnership was first announced on March 2, 2026. The ChatGPT advertising pilot formally launched on February 9, 2026.

Where: The integration operates across ChatGPT's Free and Go subscription tiers, initially in the United States and now expanding to Australia, Canada, and New Zealand. Criteo's platform operates globally across the Americas, EMEA, and APAC.

Why: Criteo characterizes ChatGPT as a high-intent discovery channel with performance characteristics - elevated conversion rates and CTRs - that distinguish it from passive social environments. For OpenAI, Criteo provides programmatic infrastructure and advertiser scale during a phase when the company is assembling its own advertising stack. For brands and agencies, the pilot offers early access to conversational AI inventory within familiar activation and measurement workflows, ahead of what appears to be a broader commercial rollout.

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