Horizon3 Raises $250M Series E at $2B Valuation to Expand AI-Powered Cybersecurity Platform

Horizon3 Secures $250 Million Series E

San Francisco-based cybersecurity startup Horizon3 has raised $250 million in Series E funding, reaching a $2 billion valuation, more than tripling its valuation over the past 14 months.

The round was backed by existing investors NightDragon and NEA, reflecting growing investor confidence in AI-powered cybersecurity as enterprises face increasingly sophisticated AI-driven threats.

AI-Powered Penetration Testing Platform

Founded by Snehal Antani and Anthony Pillitiere, Horizon3 develops NodeZero, an autonomous AI-powered penetration testing platform that continuously identifies security vulnerabilities across enterprise networks.

Unlike traditional penetration testing that is typically performed annually, NodeZero continuously evaluates live production environments without disrupting business operations.

The platform is designed to:

• Continuously scan enterprise infrastructure

• Simulate real-world cyberattacks

• Identify exploitable vulnerabilities

• Help security teams prioritize remediation

• Perform autonomous penetration testing without operational downtime

According to the company, NodeZero has completed more than 310,000 production security tests without causing operational disruptions.

Growing Enterprise Demand

Horizon3 said demand has accelerated as organizations strengthen their defenses against AI-enabled cyber threats.

The company reported:

• Nearly $100 million in annual recurring revenue (ARR) last year

• 120% year-over-year revenue growth

• Approximately 7,200–7,300 customers worldwide

Its customer base ranges from managed service providers serving small businesses to Fortune 10 enterprises.

Funding to Support Global Expansion

The new capital will be used to expand Horizon3's international operations, strengthen research and development, and grow its global partner ecosystem.

The company has recently expanded into:

• Amsterdam

• Australia

• Singapore

Strategic investors now include EDBI, SAIC, and Qualcomm, supporting the company's continued growth across enterprise and government markets.

As AI-driven attacks become more sophisticated, Horizon3 aims to help organizations move from periodic security assessments toward continuous autonomous security validation.