Horizon3 Raises $250M at $2B Valuation for AI Cybersecurity Platform

Cybersecurity firm Horizon3 closed a $250 million Series E round that pushed its valuation past $2 billion, according to a Monday press release from the company.

The new valuation represents a more than threefold increase from the $650 million figure Horizon3 achieved roughly a year earlier in its Series D funding.

NightDragon and NEA co-led the investment round.

The company's NodeZero platform deploys autonomous attacks against a client's live production systems to uncover security weaknesses before real attackers can exploit them.

Once vulnerabilities surface, NodeZero delivers remediation guidance and immediately confirms when fixes take effect. The platform can also identify when AI-powered adversaries have penetrated an organisation's environment.

Pentesting — short for penetration testing — refers to the practice of simulating sophisticated cyberattacks to discover and patch security flaws before malicious actors exploit them.

Horizon3 posted 120% year-over-year growth in annual recurring revenue and now serves more than 7,000 organisations worldwide, including four Fortune 10 companies.

The fresh capital will fund expansion of the company's sales operations, entry into Singapore and Australia, and a broader footprint across the EMEA region. Horizon3 also plans to accelerate product development.

We're about to see an explosion of vulnerabilities, most of which won't matter, but a small percentage will be immediately exploitable, CEO Snehal Antani said. > The goal of running pentests isn't to find problems, it's to quickly fix exploitable problems that matter.

NightDragon founder Dave DeWalt noted that Horizon3 pioneered the concept of AI-driven cyber warfare, adding that this future has now materialised.

The FBI's Internet Crime Complaint Center received 22,364 complaints referencing AI in 2025, underscoring the scale of AI-enabled cybercrime.

AI tools are making software vulnerabilities easier to discover, and the next competitive edge may belong to firms that can adjust permissions, transaction limits, and system access before those flaws escalate into damaging events.