Horizon3 Raises $250 Million at More Than $2 Billion Valuation

Horizon3, a cybersecurity startup, raised $250 million in a Series E round at a valuation exceeding $2 billion, more than tripling its June 2025 valuation of $650 million. NightDragon and NEA co-led the round, with participation from seven new investors and five returning backers. The company plans to use the funds for international expansion and AI product development, including autonomous defensive agents.

Horizon3 Raises $250 Million at More Than $2 Billion Valuation - Horizon3’s $250 million Series E more than tripled its valuation from $650 million in June 2025 to above $2 billion. 1 https://horizon3.ai/news/press-release/horizon3-raises-250m-series-e-at-2b-valuation-to-lead-the-ai-vs-ai-cybersecurity-era/ - NightDragon and NEA co-led the round, joined by seven new investors and five returning backers. 1 https://horizon3.ai/news/press-release/horizon3-raises-250m-series-e-at-2b-valuation-to-lead-the-ai-vs-ai-cybersecurity-era/ - Horizon3 says NodeZero has conducted 310,000 production tests and serves more than 7,000 organizations; those figures have not been independently audited. 1 https://horizon3.ai/news/press-release/horizon3-raises-250m-series-e-at-2b-valuation-to-lead-the-ai-vs-ai-cybersecurity-era/ Cybersecurity startup Horizon3 has raised $250 million at a valuation of more than $2 billion, giving the maker of the NodeZero automated security-testing platform fresh capital for international expansion and AI product development. 1 https://horizon3.ai/news/press-release/horizon3-raises-250m-series-e-at-2b-valuation-to-lead-the-ai-vs-ai-cybersecurity-era/ Existing investors NightDragon and NEA co-led the Series E. New investors included Acrew Capital, Blue Cloud Ventures, Demeter Group, Singapore’s EDBI, PSG, SAIC and Sapphire Ventures. Craft Ventures, Prosperity7 Ventures, Qualcomm Ventures, Ridge Ventures and SignalFire also participated. 1 https://horizon3.ai/news/press-release/horizon3-raises-250m-series-e-at-2b-valuation-to-lead-the-ai-vs-ai-cybersecurity-era/ From periodic tests to repeated validation NodeZero attempts to exploit weaknesses across identities, infrastructure, cloud systems and applications, then maps attack paths, recommends fixes and retests the environment. Horizon3 says the platform has completed 310,000 tests without disrupting customers’ production systems, a company claim that has not been independently verified. 1 https://horizon3.ai/news/press-release/horizon3-raises-250m-series-e-at-2b-valuation-to-lead-the-ai-vs-ai-cybersecurity-era/ Automated security validation differs mainly from a conventional penetration-testing engagement in cadence and execution. NIST defines penetration testing as evaluators mimicking real attacks to find combinations of vulnerabilities that can compromise systems. Platforms such as NodeZero automate parts of that process so companies can run tests repeatedly after configuration changes or repairs, rather than relying only on a periodic, human-led assessment. 3 https://csrc.nist.gov/glossary/term/penetration testing Customer reviews on G2 commonly cite repeatable testing and remediation guidance as benefits, while some users report limits in reporting depth, scope and coverage. Several displayed reviews were collected through seller invitations or incentives, so they provide useful operational context rather than independent proof of Horizon3’s performance claims. 4 https://www.g2.com/products/nodezero-from-horizon3-ai/reviews Sales expansion and defensive agents Horizon3 said annual recurring revenue grew 120% year over year and that it serves more than 7,000 organizations, including four Fortune 10 companies. Chief Revenue Officer Matt Hartley told TechCrunch that the company approached $100 million in annual recurring revenue in 2025 and had roughly 7,200 to 7,300 customers. 1 https://horizon3.ai/news/press-release/horizon3-raises-250m-series-e-at-2b-valuation-to-lead-the-ai-vs-ai-cybersecurity-era/ 2 https://techcrunch.com/2026/08/03/horizon3-hits-2-billion-valuation-with-250m-series-e-as-ai-threats-escalate/ The startup plans to spend the proceeds on sales, marketing and channel partnerships; entry into Australia and Singapore; further EMEA expansion; and autonomous defensive agents designed to remediate findings from NodeZero tests. Horizon3 did not disclose how much capital it will allocate to each area. 1 https://horizon3.ai/news/press-release/horizon3-raises-250m-series-e-at-2b-valuation-to-lead-the-ai-vs-ai-cybersecurity-era/ Companies mentioned Further sources 1 Horizon3, “Horizon3 Raises $250M Series E at $2B+ Valuation to Lead the ‘AI vs.… ↗ https://horizon3.ai/news/press-release/horizon3-raises-250m-series-e-at-2b-valuation-to-lead-the-ai-vs-ai-cybersecurity-era/ 2 TechCrunch, “Horizon3 hits $2 billion valuation with $250M Series E as AI threa… ↗ https://techcrunch.com/2026/08/03/horizon3-hits-2-billion-valuation-with-250m-series-e-as-ai-threats-escalate/ 3 National Institute of Standards and Technology, “Penetration Testing” glossary. ↗ https://csrc.nist.gov/glossary/term/penetration testing 4 G2, “NodeZero from Horizon3.ai Reviews 2026.” ↗ https://www.g2.com/products/nodezero-from-horizon3-ai/reviews The stories that matter, in one email. Free — unsubscribe anytime.