Forrester warns AI marketing spend lacks business impact

Forrester has published research showing that most organisations are failing to link AI spending in marketing to measurable business outcomes. Fewer than one-third directly connect those initiatives to revenue or profit.

The findings highlight a gap between investment and accountability as AI becomes more deeply embedded in how customers discover, evaluate and buy products and services. Marketing leaders are under pressure to keep driving growth while adapting to changes in discovery, buying behaviour and internal operations.

Generative AI search tools and other answer engines are also changing how brands are discovered. This is reducing marketers' visibility across parts of the buyer journey, particularly in conversational search and so-called zero-click experiences, where users get answers without visiting a brand's website.

At the same time, AI is changing the structure of marketing teams. Rather than relying mainly on new hires to increase output, organisations are increasingly turning to software, automation and AI systems.

Forrester found that 39% of B2C marketing decision-makers plan to significantly increase technology investment, while 28% expect similar increases in headcount. Among B2B chief marketing officers, 63% have slowed hiring as they reassess talent needs in organisations shaped more heavily by AI.

Buying shift

The research also suggests that AI systems are becoming participants in purchasing decisions, not just tools used by marketers. In B2B markets, 94% of buyers report using generative AI or conversational search tools as a primary source of information.

It also found that 88% of B2B decision-makers say their organisations are adopting or planning to adopt AI agents. As a result, marketers must increasingly consider how to influence both human buyers and machine-led intermediaries involved in qualification, engagement and decision-making.

The report frames this as a broader shift in the role of the chief marketing officer. Instead of focusing mainly on campaign delivery and brand activity, CMOs are being pushed towards more direct growth accountability tied to business performance.

Forrester found that 80% of US B2C marketing executives believe their 2026 corporate profits will largely come from organic growth. That expectation increases pressure on marketing leaders to show their contribution at an enterprise level rather than through proxy measures alone.

Role changes

Mike Proulx, Vice President and Research Director at Forrester, said the rise of AI could strengthen rather than diminish the position of the chief marketing officer.

"AI doesn't signal the end of the CMO role - quite the opposite. It creates an opportunity for CMOs to step into a new level of growth accountability, one that many have been pushing toward for years," Proulx said.

He said AI agents are set to take on more of the operational and optimisation work that has historically occupied marketing teams, leaving senior leaders to make broader decisions on investment and oversight.

"As AI agents take over orchestration, execution, and optimization, the CMO role moves up - not out. CMOs will spend less time managing programs and campaigns, and more time making enterprise-level trade-offs about where to invest, where to automate, and where human judgment still matters. In an AI-mediated buying environment, growth is no longer something marketing supports; it's something marketing helps design, measure, and govern across the enterprise," he said.

The report presents AI less as a new objective for marketing than as a force reshaping how existing objectives are met. For CMOs, that means proving whether technology spending produces tangible returns, even as the channels, workflows and decision-makers involved in buying become harder to track.

Fewer than one-third of companies currently make a direct connection between their AI initiatives and revenue or profit.