Horizon3 Secures $250 Million Series E Funding for AI-Powered Cybersecurity Platform

Cybersecurity company Horizon3 has successfully raised $250 million in its Series E funding round, resulting in a valuation of $2 billion, more than tripling its previous value within 14 months. The San Francisco-based firm received support from existing investors NightDragon and NEA. The financing comes at a time when two major AI research labs revealed that their models had breached systems outside their intended scope.

Horizon3, which has dedicated six years to developing AI specifically designed to probe networks for vulnerabilities in a controlled, authorized manner, is experiencing increasing demand from enterprises. With AI-driven attacks on the rise, companies are urgently seeking to test their defenses at scale, a gap that traditional security vendors have largely overlooked. Horizon3's NodeZero platform boasts two main strengths: the capability to test live systems without interrupting operations, a feature that other AI-powered tools have struggled to consistently deliver, and the ability to continuously scan an entire infrastructure rather than just 2-3% on an annual basis.

The company achieved nearly $100 million in annual recurring revenue last year with a 120% year-over-year growth and anticipates further acceleration in growth this year. Horizon3 has invested around $100 million in R&D to develop automated systems built to remain predictable and controllable, addressing concerns raised by recent breaches at AI labs. The company has conducted 310,000 production security tests with no disruptions, establishing what it calls 'AI Hackers,' fully autonomous penetration testing.

Horizon3's founders, Snehal Antani and Anthony Pillitiere, established the company to automate repetitive security assessments after experiencing challenges with continuous security testing at the Joint Special Operations Command, due to resource constraints. With the new funding, Horizon3 is expanding internationally, opening new offices in Amsterdam, Australia, and Singapore, and is set to increase R&D spending, while building a partner network.

The company has approximately 7,200 to 7,300 customers, ranging from managed service providers serving small businesses to Fortune 10 enterprises. The company claims an addressable market of tens of billions of dollars, in line with industry estimates of the broader cybersecurity market, which was valued at $271.9 billion in 2025 and is projected to reach $663.2 billion by 2033, according to Grand View Research.