Onyx Security, a company that sells a control layer for AI agents used inside large businesses, raised a $113m Series B round announced on 29 July 2026. Bessemer Venture Partners led the investment.
Cyberstarts, TCV, Conviction, FirstMark, Vintage, QuantumLight and G Squared also took part, according to the company's press release. Onyx did not state a valuation, but Calcalist's CTech reported it at about $640m, a several-fold increase on the previous round.
The round brings total funding to $153m. Onyx said revenue has quadrupled since it left stealth four months ago, though it did not disclose revenue figures.
What Onyx Security does
Onyx describes its product as a secure AI control plane. It lets a company discover which AI agents are running, set limits on what they may do and correct them in real time. According to the release, its own models monitor each step of an agent's reasoning and intervene when an action is unintended or malicious.
Customers use it to oversee both third-party agents and agents built by their own engineers. The company said dozens of large enterprises, including Fortune 500 firms in banking, technology, insurance and energy, use the platform. Revolut is named as a customer; Uros Solar, its head of security engineering, said Onyx gives the visibility and control needed to use coding agents safely.
The release also says Anthropic announced an integration with Onyx in June, and that dozens of other AI providers have integrated with the platform.
Who is behind it
CTech reported that Onyx was founded in 2024 by Maxim Bar Kogan, the chief executive, and Gil Elbaz. Bar Kogan is a veteran of the Israeli military's Unit 8200 and a former vice president of product and engineering at Mixtiles. Elbaz is an AI entrepreneur who served in the Israeli Air Force's Operational Technology Unit.
The company is based in New York and Tel Aviv. CTech put its headcount at more than 80, with staff in Israel, the United States and Canada.
Bar Kogan said in the release that in 2025 less than one percent of actions were made by agents, and the company is building for a point where that share is far higher.
The funding so far
Before the Series B, Onyx had raised about $40m, according to CTech: a $5m seed round led by Cyberstarts and a $35m Series A. The press release gives only the $153m total.
Bessemer partner Amit Karp and Cyberstarts general partner Hila Zigman both said in the release that Onyx is building the control layer that enterprise adoption of AI will need.
What the money is for
Onyx said it will use the funds to train the next generation of its proprietary models and to scale its enterprise sales effort in the United States and beyond.
The round adds to a run of large financings for security companies aimed at AI agents, as businesses move from testing agents to giving them access to internal systems and data.
Company website: onyx.security