Onyx Security has raised $113 million in a Series B round led by Bessemer Venture Partners, valuing the startup at roughly $640 million, the company said. The financing arrives just four months after Onyx emerged from stealth with $40 million in prior funding — including a $5 million seed and a $35 million Series A.
## Rapid investor interest after stealth
Co-founder and CEO Maxim Bar Kogan said the company’s swift traction once it began selling broadly drove investor demand. He told reporters that early customer uptake exceeded expectations and allowed Onyx to accelerate fundraising far sooner than planned. Bar Kogan added that investors view AI security as one of the most important emerging segments in cybersecurity and are backing firms they believe can become category leaders.
## What Onyx builds and why it matters for AI security
Onyx develops a platform that helps enterprises deploy autonomous AI agents at scale while managing permissions, monitoring agent activity, and preventing risks tied to agent behavior. The technology traces each stage of an agent’s reasoning, enabling organizations to detect, block and remediate malicious or
