AI shifts CMOs from marketing performance to growth accountability: Forrester

A new report from Forrester argues that artificial intelligence is not changing what CMOs are accountable for – but it is fundamentally transforming how that accountability is delivered, measured, and judged at the highest levels of the business.

In “The AI CMO”, the research firm positions marketing leaders at the centre of a structural shift: from driving campaigns and performance metrics to owning the conditions under which growth is produced. The shift, it said, will require CMOs to balance a “clear, growth-anchored vision” with the uncertainty introduced by AI, while taking on a more explicit role as organisational change leaders.

The report stresses that AI does not alter the core mandate of marketing – growth – but it is redefining the execution layer. From how brands show up in customer moments to how marketing teams are structured, AI is reconfiguring workflows, talent mix, and decision-making speed.

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AI agents emerge as a new marketing audience

One of the most immediate disruptions comes from the rise of conversational “answer engines” such as ChatGPT, Claude, and Perplexity, as well as Google Gemini. These platforms are reshaping discovery and purchase journeys into zero-click experiences, reducing visibility for marketers while compressing the path to conversion.

Adoption is already significant. The report noted that roughly half of US online adults have used AI agents to ask questions and receive synthesised answers, while younger cohorts are increasingly turning to tools such as ChatGPT for product discovery. In B2B contexts, usage is near ubiquitous, with 94% of buyers reporting reliance on generative AI tools across the purchase journey.

This creates a new challenge: CMOs must win share of voice in interactions they cannot directly see or control.

Beyond reshaping customer behaviour, AI is also introducing a new stakeholder: the machine itself.

As AI agents begin to intermediate both B2C and B2B journeys, marketing strategies must expand from influencing human decision-making to shaping how algorithms evaluate, rank, and recommend brands. The report highlights that 88% of B2B decision-makers are already adopting or planning to adopt AI agents, while 43% of US consumers expect brands to market directly to their AI assistants.

This signals a shift towards “agentic marketing”, where optimisation extends beyond human perception to machine interpretation – changing how brand equity is built and measured.

Marketing capacity shifts from people to systems

The operational backbone of marketing is also undergoing change. AI is enabling execution at scale without proportional increases in headcount, moving marketing from labour-constrained to system-driven.

“Over time, I expect setting up and running our campaigns will be more and more agent based, with fewer humans turning all the knobs,” said Casey Cary, CMO at TCP Software.

Forrester’s earlier forecasts suggested that 7.5% of advertising agency jobs – around 33,000 roles – will be automated by 2030, signalling broader structural shifts across marketing organisations. Investment patterns are already reflecting this: more marketing leaders are increasing technology spend than headcount, while many are slowing hiring to assess AI’s long-term impact.

Forrester argues that the real challenge is not technological but organisational. To unlock AI’s value, CMOs must act as change leaders – reengineering how marketing functions while guiding teams through uncertainty. 

This shift brings with it a redefinition of the CMO’s core responsibilities. Growth accountability is expanding, with marketing becoming more tightly linked to enterprise outcomes as AI amplifies its ability to demonstrate impact at the C-suite level.

At the same time, execution oversight is receding, as automation takes over workflows and reduces the need for hands-on management. In parallel, brand stewardship is evolving: CMOs are now required to govern how AI systems represent their brand, introducing new risks around bias, hallucination, and consistency.

“AI is turning the CMO into a growth leader that brings together data, technology, and talent to deliver maximum impact on the business,” said Bradley Breuer, SVP of marketing at PetSmart.

At the same time, Darren Cassidy, CMO at Xerox, highlighted the operational shift: “The way that I do business tomorrow, from campaign creation to orchestration to deployment, AI is already changing the speed and the velocity of how I do that.”

A new layer of brand risk

As AI takes a more active role in content creation and decision-making, brand governance becomes more complex. The report notes that 70% of marketers have already encountered AI-related brand incidents, while 80% of brand owners are concerned about how agencies are using generative AI.

“I now have to understand what our third-party partners are doing with AI – not just from a capability standpoint, but from a brand reputation perspective. That’s an entirely new layer of responsibility,” said Mike Daum, CMO at Golden 1 Credit Union.

Ultimately, AI is tightening the link between marketing activity and business outcomes – removing layers of operational opacity and placing CMOs more directly on the hook for growth.

The report describes this as a shift towards “purer accountability”, where fewer process signals and execution details mean fewer buffers between marketing leaders and results. 

To adapt, Forrester outlines several priorities that collectively reshape how CMOs operate. Leaders are expected to engage with AI tools firsthand, using them in their day-to-day work to fully understand both their capabilities and limitations. At the same time, they must continuously reallocate their time, shifting away from supervising execution and towards making the strategic decisions that AI cannot replicate.

This transition also demands that AI fluency becomes an ongoing leadership discipline rather than a one-off capability, requiring constant learning and experimentation. Finally, leadership itself must evolve, as authority and delegation move away from traditional human oversight towards managing systems and machines.

“AI helps me grok a lot of information much faster, but I still have to check its output,” said Lynn Tornabene, CMO and chief product officer at Anteriad.

Michelle Boockoff-Bajdek, CMO at Sitecore, added: “One of my best employees is a guy named ‘Claude,’ because he does a ton of work for me. Having an AI thought partner has been the biggest step change in my world. Stuff that would have taken me weeks is now taking me hours.”

David Hamilton, CMO at SAP Concur, reinforced the urgency: “Marketing has to be constantly learning. Savvy CMOs understand AI will replace marketers that don’t understand AI.”

Forrester’s central thesis is clear: AI is embedding marketing deeper into the mechanics of growth, elevating the CMO from a function leader to a business-critical operator.

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