London-Based PolyAI Secures $86M Funding In Series D Round

Additional investors in PolyAI’s Series D included NVentures (Nvidia’s VC arm), Sands Capital, Squarepoint Ventures, Citi Ventures, Point72 Ventures, and the British Business Bank, which contributed £15 million ($20.1 million).

The London-based startup will use the funding to advance its AI technology and expand its enterprise customer base.

PolyAI serves major enterprises facing rising 24/7 call center demands and high staff turnover. The startup counts over 100 enterprise clients, including Las Vegas casinos, Hilton, Marriott, FedEx, and Unicredit.

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A University of Cambridge spinout, PolyAI has developed AI voice assistants for call centers that handle millions of calls, often sounding indistinguishable from human agents.

The assistants are designed with linguists to mimic natural speech patterns and can be customized by accent, tone, and vocabulary. They can perform tasks such as taking payments and collecting customer details.

PolyAI leverages its proprietary large language models alongside major providers like OpenAI and DeepSeek. Last year, the startup raised $50 million in a Series C round, valuing it near $500 million. The Series C was led by Hedosophia and NVentures, adding to its previous $66 million in funding from earlier investors.

Nikola Mrkšić, CEO and co-founder, PolyAI, said: "This Series D financing is proof of the industry’s confidence in our abilities and the potential of our technology.

“This investment will kick-start the next stage of our growth cycle and ensure that we can continue to deliver best-in-class technology for enterprises looking to transform their customer and employee experience.”

Chancellor of the exchequer, Rachel Reeves, said: “We are investing in companies like PolyAI so we can grow the economy and create good jobs. Our backing, combined with our world‑leading universities, strong private investment, and our AI Growth Zones makes the UK one of the best places in the world to build an AI startup."

About PolyAI

PolyAI is a leading provider of enterprise AI agents for customer service, resolving millions of inquiries for top global brands. Its lifelike, engaging AI experiences make interactions feel natural, delivering efficient, human-like support at scale.