Cybersecurity startup Horizon3 has raised $250 million in a Series E funding round, pushing its valuation to $2 billion as enterprises invest more heavily in AI-powered security amid a rapidly evolving threat landscape.

The round was led by existing investors NightDragon and NEA and comes just 14 months after the company’s previous valuation, reflecting growing demand for tools capable of continuously testing enterprise networks against increasingly sophisticated cyberattacks.

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AI Is Changing Cybersecurity

Unlike traditional penetration testing, which is often carried out once or twice a year, Horizon3’s NodeZero platform continuously scans production environments without disrupting operations. The platform uses artificial intelligence to identify vulnerabilities across an organisation’s infrastructure, helping security teams detect weaknesses before attackers can exploit them.

The company says it has already completed more than 310,000 security assessments in live environments without causing operational downtime.

Growing Enterprise Demand

The funding follows a period of accelerating adoption as organisations reassess their cybersecurity strategies in response to the rapid expansion of generative AI. As AI lowers the barrier for creating new cyberattacks, businesses are increasingly looking for automated tools capable of testing systems at a much larger scale than traditional security assessments.

According to Horizon3, the company approached $100 million in annual recurring revenue last year while growing 120% year over year.

Expansion Plans

The new capital will support Horizon3’s international expansion, including recently announced operations in Amsterdam, Australia and Singapore, while allowing the company to continue investing in research and development.

Strategic investors now include Singapore’s EDBI, defence contractor SAIC and Qualcomm, reflecting growing interest in AI-driven cybersecurity across both commercial and government sectors.

A Fast-Growing Market

The investment also highlights continued momentum across the cybersecurity industry as organisations adapt to increasingly complex AI-enabled threats. Market researchers estimate the global cybersecurity sector was worth $271.9 billion in 2025 and could exceed $663 billion by 2033, driven by rising demand for automated security, threat detection and enterprise resilience.