Enterprise browser Island raises $400M Series F at $6.4B valuation, positioning as AI agent control plane

Island announced on September 24 the close of a $400 million Series F at a $6.4 billion valuation, led by Evolution Equity Partners with participation from Sequoia, Coatue, Insight Partners, J.P. Morgan, and others, plus CrowdStrike co-founder Dmitri Alperovitch in a personal capacity. The round brings total funding past $900 million and represents a 33% step-up from the $4.8 billion valuation set at the March 2025 Series E. Island has roughly doubled annual recurring revenue each fiscal year since launching in 2022.

Originally positioned as a hardened enterprise browser, Island now describes itself as an agentic control plane governing both human employees and AI agents inside the enterprise. The Enterprise AI product adds identity controls for agents, policy guardrails and human-in-the-loop approvals, cost caps on agent spending, and unified audit trails spanning browsers, devices, applications, networks, and data. The platform uses an endpoint-outward SASE architecture delivering zero-trust network access, device posture checks, and inline data loss prevention without traditional VPNs.

Island reports eight of the world's ten largest banks as customers and currently has approximately 1,000 employees, with plans to grow to 1,500 and expand across Europe, Asia, and the Middle East. Competing approaches include Neo, which raised $100 million in July to build agent control infrastructure; Cloudflare's launch of a browser for AI agents; and Anthropic's DLP hooks added to Claude Enterprise.