London has evolved as the only ecosystem on the planet where the signals intelligence legacy of GCHQ collides directly with the limitless capital of the City. The result is a breed of startup that is sharper, faster, and more aggressive than anything emerging from the Valley.
We have moved beyond the era of passive compliance and box-ticking. The founders on this list are building offensive defence systems. They are securing the AI brains of the future, hunting money launderers on the blockchain, and turning every developer into a security grandmaster.
Here are the 10 London cybersecurity startups you need to know in 2026.
Snyk
Guy Podjarny founded Snyk to execute a radical power shift. He realised before anyone else that developers outnumber security teams by a hundred to one. Snyk handed the weapons to the coders. They built a platform that enables developers to fix vulnerabilities in real-time as they write code. With a valuation smashing through $7.4 billion, they are the undisputed kings of the developer security revolution. They integrate seamlessly into the workflow of giants like Google and Salesforce to ensure that software is born secure.
Immersive Labs
James Hadley walked out of GCHQ with a mission to turn cyber defence into a high-stakes sport. Immersive Labs has revolutionised the traditional classroom training model. They drop teams into hyper-realistic simulations of ransomware attacks and APTs. It is a cyber gym where pros test their skills against live threats. When a new zero-day hits the news, Immersive Labs has a simulation ready within hours. This is how the world’s largest banks prove their teams are battle-ready.
Elliptic
Tom Robinson and his team at Elliptic are the detectives of the dark web. They built the intelligence layer that makes crypto safe for the establishment. Their software traces billions of dollars in Bitcoin and Ethereum to flag wallets linked to terrorists and cartels. They map the flow of illicit funds across the blockchain with terrifying accuracy. Banks and governments rely on Elliptic to ensure they are not accidentally laundering money for bad actors.
Incident.io
Stephen Whitworth created Incident.io to bring order to absolute chaos. When a system goes down, panic usually sets in. Incident.io kills the panic. It runs entirely inside Slack to automate the entire crisis management process. It assigns roles, tracks updates, and generates timelines instantly. They are the digital firefighters for high-growth companies like Monzo and Vinted. They turn a potential PR disaster into a streamlined engineering problem.
SenseOn
David Atkinson built SenseOn to cure the industry of dashboard fatigue. Security analysts are drowning in false alarms from dozens of disconnected tools. SenseOn deploys AI triangulation to monitor everything simultaneously. It monitors endpoints, networks, and clouds simultaneously to spot the subtle patterns of an intruder. It ignores the noise and only flags the genuine threats. This is the autonomous immune system for the modern enterprise.
Metomic
Rich Vibert founded Metomic to lock down the invisible data sprawl. Your employees are sharing secrets on Slack, Notion, and Google Drive every single minute. Metomic scans these collaboration tools to hunt for credit card numbers and passwords. It automatically redacts sensitive information and educates users in the moment. They are the guardians of the SaaS ecosystem, ensuring that agile collaboration does not result in a massive data leak.
Cado Security
James Campbell and Chris Doman launched Cado Security to bring forensics into the modern age. Old school investigation tools fail in the cloud because containers disappear in seconds. The Cado platform is a time machine for the cloud. It automates the capture of data from AWS and Azure to reconstruct cyberattacks instantly. It allows responders to investigate a breach at the speed of the cloud rather than waiting days for server logs.
Mindgard
Peter Bentley spun Mindgard out of UCL to tackle the most dangerous frontier in tech. They are securing the AI brain itself. As companies rush to deploy large language models, they open themselves up to prompt injection and jailbreaking. Mindgard provides the automated red teaming infrastructure to test these models to their breaking point. They ensure that your corporate AI cannot be tricked into revealing trade secrets or behaving maliciously.
CyberSmart
Jamie Browder built CyberSmart to defend the undefended. Small businesses are prime targets for hackers, but cannot afford a bespoke security team. CyberSmart automates the entire digital defence posture for SMEs. Their software runs continuous checks on devices to ensure the perimeter is solid. They have democratised state-grade security for thousands of businesses that were previously left vulnerable.
Garrison
David Garfield created Garrison to rethink security from the hardware up. They developed a unique hardsec technology that physically isolates web browsing. When you click a link, Garrison executes the code on separate hardware and sends you a safe video feed. It means malware simply cannot jump the air gap to your device. This is the nuclear option for security, used by governments and critical infrastructure providers who cannot afford a single breach.
