A London-based startup that helps casinos, banks and medical companies field and answer calls from customers using artificial intelligence has raised a new round from existing investors that now values the company at $750 million.
PolyAI raised $86 million in a Series D funding round co-led by existing investors Georgian, Hedosophia and Khosla Ventures. The valuation of the University of Cambridge spinout has jumped 50% from $500 million at its last fund raise in May 2024. PolyAI, which was founded in 2017, has raised $200 million to date with its new round.
Investors have plowed far more money into similar startups that promise to replace call centers and help desk employees that answer customer service calls or take reservations and bookings. AI startup Sierra, cofounded by Silicon Valley veteran and OpenAI chairman Bret Taylor in 2023, surged to a $10 billion valuation after closing a $350 million funding round in September, while its San Francisco-based rival Decagon leapt to a $1.5 billion valuation in June. And even its European competitors, like Berlin-based rival Parloa are reportedly in talks to raise $200 million on at least $2 billion, Bloomberg reported in December.
“Our vision has always been to make voice AI so good that the best companies want to use it to be even better and be recognized for having the best customer service,” said Nikola Mrksic, cofounder and CEO of PolyAI.
Nvidia-backed PolyAI is now managing customer calls about power outages for PG&E, California’s largest energy company, dial-ins to register and manage new cards for Italian bank Unicredit and front desk queries and restaurant bookings for Las Vegas casinos like Caesars and Golden Nugget.
For Mrksic, voice AI isn’t just about cutting the cost of human call center agents (though he says his tools are doing the work of 1,000 workers at some companies). His agents might sound human but the technology is scalable, making it easier for clients like PG&E to handle huge spikes in call volumes, like during the February 2024 California floods.
PolyAI, which has its own voice AI models unlike rivals that are plugged into OpenAI, voice-specific AI lab ElevenLabs or other large AI companies, says it has also helped customers grow revenue by assigning artificial voice agents to tasks that wouldn’t be economical for human agents. “Our AI picks up every phone call, they always book you in and they never forget to upsell you,” said Mrksic, who previously worked with Apple on its voice assistant Siri. “It helps companies become the best version of themselves.”
That’s translated into a big jump in earnings for PolyAI. Mrksic said that he expects annualized recurring revenue (ARR) to double this year to $40 million, while revenues from its U.S.-based clients have nearly tripled. (ARR has become an increasingly popular benchmark for software and AI startups, even as some investors have grumbled that the definition has been stretched to create more headline growth by multiplying out revenue from one deal across an entire year, even if it was with trial customers.)
Unlike its American rivals, PolyAI is required to publish audited financial statements, like all British companies above a certain scale. These U.K. corporate filings show that PolyAI’s GAAP revenue exploded in the 12 months to January 31, 2025 to $15 million from $8.9 million over the same period of 2024. PolyAI’s 2025 revenue won’t be public until mid 2026 at the earliest.
Sierra announced in November that it had hit $100 million in ARR while Forbes estimated that Decagon would make $12 million in 2025. The 25x multiple on PolyAI based on its new valuation looks conservative with its Bay Area rivals now at over 100x. That’s still a long way north of the 8x multiple listed software as a service companies are valued at by public markets investors. “When the chairman of OpenAI enters your space to go head-to-head it is validating,” said Mrksic. “He’s really gentrified the space because we all know now that this is a high end application for AI.”
PolyAI’s U.K. corporate filings also show that its losses widened to $26.6 million up from $23.8 million in the 12 months to January 2024.
