Horizon3 Raises $250M Series E at $2 Billion Valuation
Horizon3 raises $250M Series E at a $2B valuation to scale NodeZero continuous pentesting, expand overseas and counter a surge in AI-driven cyber threats.
Horizon3 announced a $250 million Series E financing that values the cybersecurity startup at $2 billion, a more-than-threefold increase in just over a year. The San Francisco firm said the round was led by returning backers and includes strategic investors across defense, semiconductors and sovereign funds. The funding will be used to expand the company’s NodeZero platform, accelerate international growth and deepen research and development.
Largest Round Since Rapid Revaluation
Horizon3’s new capital follows a rapid climb in private-market value, accelerating after the company recorded strong commercial traction. The company said it neared $100 million in annual recurring revenue last year while sustaining roughly 120% year‑over‑year revenue growth. Investors returning to the cap table include NightDragon and NEA, alongside new strategic names such as Singapore’s EDBI, SAIC and Qualcomm.
The size and composition of the round signal investor confidence in automated offensive security as an enterprise-grade product. Company executives framed the raise as runway for both geographic expansion and continued investment in predictable, controllable AI systems built for security testing.
NodeZero Targets Continuous, Non‑Disruptive Testing
Horizon3 emphasized NodeZero’s capacity to run live, authorized penetration tests without taking production systems offline — a capability executives say many automated tools have not consistently delivered. The platform is designed to scan entire infrastructures on an ongoing basis rather than sampling a small portion of assets once a year, a shift the company says customers now demand.
The startup reported it has executed more than 310,000 production tests without causing operational outages, and it markets an autonomous testing capability it describes as “AI Hackers.” Company leaders say those automated tests are engineered to remain predictable and controllable, reflecting roughly $100 million invested in research and development to avoid runaway behaviors.
Enterprise Demand Rises as AI Threats Grow
The fundraise comes as enterprises reassess defensive postures after high‑profile incidents involving AI systems and security testing programs. Executives at Horizon3 argue the same AI tools that help defenders also lower the barrier for attackers to develop exploits faster, increasing urgency for continuous validation of defenses. That dynamic, they say, has changed procurement priorities from periodic assessments toward frequent, broad coverage.
Chief revenue officers at the firm report heightened customer interest in capabilities to detect AI‑enabled activity and to understand how AI deployments might alter risk profiles. Organizations that rushed to insert AI across workflows are now asking more pointed questions about containment, oversight and the potential for unintended consequences.
Revenue Trajectory and Customer Base
Horizon3 described a rapidly expanding commercial footprint, counting roughly 7,200 to 7,300 customers that span managed service providers for small businesses up to Fortune 10 enterprises. The company said the diversity of its clients underscores demand across sectors and company sizes for continuous vulnerability discovery and validation.
Executives told investors the business is poised to accelerate growth this year, building on the ARR milestone and strong renewals. They also emphasized that human penetration‑testing firms remain relevant, but that customer expectations are shifting toward more frequent and comprehensive scanning.
Strategic Investors and Global Footprint
Beyond traditional venture capital, Horizon3’s new investors include strategic and regionally focused organizations, a mix the company highlighted as validation of its cross‑sector relevance. The round brings closer ties to defense and semiconductor ecosystems, and it follows recent geographic moves that include a new Amsterdam base opened in June 2026 and planned offices in Australia and Singapore.
Leadership said proceeds will fund both local market expansion and a partner network designed to accelerate adoption, particularly in regions where customers require integrated services and compliance support. The company signaled continued heavy R&D spending to advance automation and reliability.
Market Size and Competitive Context
Horizon3 projects an addressable market in the tens of billions of dollars and situates that opportunity within broader forecasts for cybersecurity spending. Industry estimates put the global market in the hundreds of billions, and Horizon3 argues its continuous, AI‑driven approach addresses gaps left by annual testing models and legacy vendors.
Company executives framed their primary competition not as other point products but as the incumbent model of infrequent human testing. They expect a gradual rebalancing in which many customers retain human‑led assessments while adopting automated, continuous testing to track whether security postures are actually improving over time.
Horizon3 plans to deploy the new capital to scale NodeZero, deepen its partner and enterprise programs and expand operations overseas as enterprises contend with more frequent, AI‑assisted attacks. The round positions the company to sell more broadly into regulated and defense‑adjacent markets while continuing to market autonomous testing as a complement to, not a replacement for, human expertise.
