Onyx

AI Security · Cybersecurity · Enterprise AI

Milestone

Onyx raises $113M Series B at $640M valuation for AI agent security

The raise closed just four months after stealth, showing investors racing to fund runtime controls for autonomous AI agents.

• Onyx Security raised $113 million in a Series B round led by Bessemer Venture Partners, valuing the Israeli startup at roughly $640 million.
• Onyx builds a 'Secure AI Control Plane' that discovers AI agents operating across browser, endpoint, SaaS and cloud systems and inspects every action before it takes effect.
• The Series B follows a $5 million seed and $35 million Series A led by Conviction, disclosed when Onyx emerged from stealth in March 2026, bringing disclosed funding to roughly $153 million.
• Onyx says its platform already secures more than 1.1 million AI agents and inspects over 66 million AI sessions in real time, though it hasn't disclosed revenue or customer counts.
• Anthropic integrated Onyx's technology in June to help its enterprise customers adopt AI agents more securely, an early validation point for the startup's approach.
• As AI agents inherit corporate credentials and act at machine speed, investors are betting that governing what those agents do at runtime becomes as large a security category as endpoint or cloud protection was in prior platform shifts.
• Onyx plans to use the funding to advance its underlying AI models and expand sales, business development and marketing teams in the US and internationally.