Island secures $400M funding, reaches $6.4B valuation amid AI security demand

Island, the cybersecurity startup that builds enterprise browsers, just raised $400 million in a Series F round that values the company at $6.4 billion. For a company founded in 2020, that’s the kind of trajectory that makes even seasoned venture capitalists do a double take. The round was led by Evolution Equity Partners, with existing backers Prysm Capital and Sequoia Capital also participating. The capital will fund expansion of Island’s core platform, with a particular focus on securing AI agents operating inside enterprise environments. From $3B to $6.4B in two years Island’s valuation history reads like a startup’s fever dream. The company was valued at $3 billion in 2024, then $4.8 billion after raising $250 million in March 2025. Now it sits at $6.4 billion, more than doubling its valuation in roughly two years. Island reported approximately $200 million in annual recurring revenue as of September 2026, reflecting roughly 100% year-over-year growth. The company now employs around 1,000 people, headquartered in Dallas with operations in Israel. Its client roster includes eight of the world’s ten largest banks, along with names like Citi, Pfizer, and T-Mobile. Total enterpris...