Autonomous security solutions startup Horizon3.ai Inc. today announced it has raised $250 million in a Series E round on a valuation of more than $2 billion to build out its sales operation and expand into Australia and Singapore. Horizon3.ai closed its Series D in June 2025 at a valuation of $650 million.

Horizon3.ai’s NodeZero platform attacks its customers’ own networks. The tests run against live production systems, and Horizon3.ai says nothing breaks. A single run chains weak credentials, misconfigurations and identity gaps into a working attack path, the same sequence a real intruder would use. Fix guidance comes with the findings. NodeZero re-runs the test afterward to confirm the path is closed.

NodeZero can also seed an environment with honeypots while it tests. Horizon3.ai sells the decoys as a cheap way to catch an AI-driven attacker that is already inside a network.

Horizon3.ai says NodeZero is now used by more than 6,500 organizations, up from about 3,000 at the Series D. Customers include the U.S. National Security Agency, the Cybersecurity and Infrastructure Security Agency, four Fortune 10 companies, multinational banks and healthcare networks. Annual recurring revenue grew 120% year-over-year, and the platform has now run upwards of 300,000 pentests in production, a volume of attack data the company treats as its hardest asset for a rival to copy.

“We invented the concept of AI Hackers and spent six years earning the right to autonomously pentest the most critical and sensitive networks in the world,” said Snehal Antani, co-founder and chief executive of Horizon3.ai. He added that the round gives the company fuel to scale as the leader of what he calls the “AI vs. AI” era.

Antani started the company in 2019 with Anthony Pillitiere. Antani had been chief technology officer at Splunk Inc. Pillitiere came out of U.S. Special Operations Command, where he served as deputy chief technology officer.

Most of the new capital goes to hiring in sales, marketing and channel, aimed at enterprise, mid-market and federal buyers. Singapore and Australia are the first stops in an international push that also takes in more of Europe, the Middle East and Africa. The rest funds autonomous blue-team agents, software meant to remediate what NodeZero finds without waiting on a human.

Existing investors NightDragon and New Enterprise Associates Inc. co-led the round. New backers Acrew Capital Management, Blue Cloud Ventures, EDBI Pte. Ltd., Demeter Group, PSG Equity, SAIC Ventures and Sapphire joined, along with returning investors Craft Ventures Management, Qualcomm Ventures, Ridge Ventures and SignalFire. NightDragon founder and Chief Executive Dave DeWalt, who previously ran FireEye and McAfee, takes a board seat alongside NightDragon Managing Director Morgan Kyauk. DeWalt said Horizon3.ai’s platform is “fundamentally reshaping how the world defends its data.”

The Series E brings Horizon3.ai’s total funding to $428.5 million.

Image: Horizon3.ai