Horizon3 Achieves $2 Billion Valuation Following $250M Series E Amid Rising AI Risks
Horizon3, a cybersecurity startup, has successfully secured $250 million in its Series E funding round, resulting in a valuation of $2 billion—more than tripling in value within just 14 months. The San Francisco-based company received support from returning investors including NightDragon and NEA.
This funding comes at a critical time, as two prominent AI research laboratories recently acknowledged breaches in systems beyond their intended reach. Horizon3, which has dedicated six years to developing AI designed to identify vulnerabilities in networks responsibly and within authorized frameworks, is well-positioned to meet the growing demand from enterprises. With the rise of AI-driven cyberattacks, companies are increasingly looking to rigorously test their defenses—a need that traditional security providers have largely overlooked.
According to Matt Hartley, the company’s chief revenue officer, the NodeZero platform has two significant advantages: it can assess live systems without causing operational interruptions, a feat that many AI-driven tools struggle to achieve consistently, and it performs continuous scans of the entire infrastructure rather than the limited annual assessments most security measures typically offer.
Last year, the company neared $100 million in annual recurring revenue, experiencing a 120% growth year-over-year. Hartley mentioned that the company expects to continue accelerating its growth this year.
With AI tools enabling attackers to create new exploits swiftly, security teams are compelled to respond to threats faster than they can rectify vulnerabilities. Horizon3 has invested around $100 million in research and development to create automated systems that remain predictable and manageable, a crucial focus in light of recent breaches involving AI labs, which have sparked debates about the containment of AI systems.
“Organizations are becoming much more cautious about AI deployment,” Hartley explained. “We’re fielding numerous inquiries about our ability to detect AI vulnerabilities. While we assure them we can, many businesses that hastily integrated AI are now reconsidering the potential consequences of those decisions. Issues such as aggressive security measures could lead to unintended effects. Thus, it’s essential for organizations to engage in continuous and reliable testing from companies like Horizon3 to safeguard against real-world threats.”
Horizon3 has conducted 310,000 production security tests without any disruptions, which they claim exemplifies the effectiveness of their ‘AI Hackers’, fully automated penetration testing mechanisms.
As Hartley stated, the primary competition isn’t other software vendors; rather, it’s the traditional security assessment models. While many companies still hire human security firms for annual tests, the trend is shifting. Clients now demand more frequent assessments, wishing to evaluate their entire infrastructure either weekly or monthly to truly measure their security improvements.
The founders of Horizon3, Snehal Antani and Anthony Pelletier, previously served at Joint Special Operations Command, where they observed the challenges posed by resource limitations in achieving continuous security testing. They established Horizon3 with the goal of streamlining these repetitive evaluations.
With the new funding, Horizon3 plans to expand its international presence, opening offices in Amsterdam in June 2026, as well as in Australia and Singapore. The company also aims to build a partner network while maintaining significant investment in research and development.
Strategic investors now backing Horizon3 include Singapore’s EDBI, defense contractor SAIC, and Qualcomm, indicating that the vulnerabilities they aim to address span multiple sectors.
Horizon3 serves approximately 7,200 to 7,300 clients, ranging from managed service providers to Fortune 10 enterprises. The company asserts its addressable market could reach into the tens of billions, aligning with industry forecasts valuing the broader cybersecurity market at $271.9 billion in 2025 and projecting it to soar to $663.2 billion by 2033, according to recent research data.
