AI accounting startup Rillet hits $1B valuation after $100M raise

Just a day after announcing a $100 million funding round that pushed the company’s valuation to $1 billion, Rillet co-founder and CEO Nicholas Koop is visibly assured during a video call. The timing is no accident. With the United States facing a pronounced shortage of qualified accountants, demand for his AI-native accounting platform has surged so rapidly that the fresh capital was secured in under 48 hours, without any active fundraising effort.

Rillet stepped out of stealth two years ago and has since accumulated $200 million in backing from heavyweight investors including ICONIQ, Andreessen Horowitz, and Sequoia. The platform now serves 600 customers, many of whom are actively replacing entrenched systems from Oracle and NetSuite, according to Koop.

The latest round came together after a routine board meeting a few weeks prior. Rillet presented its performance since the $70 million Series B last summer, and the numbers were striking. Annualized revenue had doubled in a single quarter, new clients were signing on (including numerous public companies), and a strategic alliance with EY was underway to bring AI tools into the auditing giant’s workflow. Koop emphasized that these clients are not running small pilot programs; they are ripping out competitor software from Intuit, NetSuite, and Oracle entirely.

Following that presentation, the phones lit up. Within 48 hours, the Series C was oversubscribed and Rillet had achieved unicorn status, a feat Koop says was never part of the plan.

Seth Pierrepont, general partner at ICONIQ who led the round, acknowledged the speed but pushed back on the notion that it was impulsive. “It wasn’t a cold start,” he said. Pierrepont, who also backed the Series B and now joins Rillet’s board, noted that the company had already demonstrated its ability to outmaneuver incumbents that have dominated the category for decades. “A year of watching the team deliver on that made doubling down and leading the Series C an easy call.”

Julien Bek, the lead investor for Sequoia, echoed that sentiment. While the 48-hour timeline might appear hasty from the outside, the decision to reinvest was straightforward given the growth trajectory. “Rillet’s initial wedge is accounting, but ultimately they are reinventing the entire finance function,” Bek said, adding that agentic finance could become “one of the largest application software opportunities of the AI era.” Sequoia led the Series A last summer, and Bek explained that when the opportunity arose, they already possessed all the context needed.

Rillet sits at the forefront of a wave of AI-native startups challenging legacy software providers. Earlier this year, public software stocks took a hit as investors grew wary of AI’s disruptive potential. Koop believes the concern is legitimate. “AI is going to come hard at these legacy players,” he said, because it offers customers compelling alternatives.

The platform itself was designed with AI agents in mind, not human operators. Humans work alongside these agents on corporate bookkeeping tasks. The client roster spans from laundromats to the NFL Hall of Fame, and the migration pattern is telling: roughly 50% of customers come from Intuit, 30% from NetSuite and Sage Intacct, and 20% from Oracle, SAP, Workday, and Microsoft products.

Handling sensitive financial data requires rigorous security measures, Koop stressed. Rillet offers model routing, allowing customers to direct requests to their preferred foundational model, whether from OpenAI or Anthropic. A protective harness ensures these models cannot train on client data. There is also no cross-training between customers, keeping each client’s information proprietary. The agents come equipped with memory, storing historical actions to refine their own processes.

About three months ago, Rillet introduced a governance feature that enables accountants to review and audit every decision an AI agent makes, including the specific numbers pulled and the calculation methods used. Koop admitted this was technically challenging, as the team had to compress vast amounts of agent activity into a format humans could easily interpret. The feature only became feasible recently because AI agents have advanced so quickly, now handling multi-step workflows over extended periods. That increased capability makes auditing their actions even more critical for clients.

“We barely scratched the surface of potential and opportunity that this technology has,” Koop said.

Current regulations for public companies mandate that a human approve every transaction executed by an AI agent. Koop believes regulators and industry leaders are closely monitoring how accounting adapts to these new tools. He remains optimistic that future rules will evolve to align with the technology’s trajectory. “It’s a very normal process,” he said, comparing it to the advent of cloud computing and the gradual familiarization that followed.

On the subject of job losses, Koop dismisses the idea that AI will trigger mass displacement in accounting anytime soon. A recent Stanford report found no evidence of widespread displacement yet, and Koop insists Rillet is not a human replacement, even for junior accountants. Instead, the platform automates the profession’s grunt work, freeing people to focus on higher-value analysis.

The talent shortage in the field is well documented. The number of accounting graduates has declined since at least 2010, and a recent Controllers Council Organization report found that 61% of finance leaders struggled to hire finance, accounting, and CPA talent over the past year. The reasons are clear: long hours, a demanding career path, and pay that often fails to match the workload.

Meanwhile, the Bureau of Labor Statistics projects accounting-related roles will grow by at least 5%, adding 72,800 jobs by 2034. The BLS also expects AI to increase demand for accountants, noting that automation of routine tasks like data entry will make advisory and analytical duties more prominent.

“I just don’t see people losing their job anytime soon,” Koop said. “These people have started their professions to help businesses make better financial decisions. We can fully enable them to do that.”