Cybersecurity defence companies in the UK
We track 17 cybersecurity companies in the UK, most of them in London and Belfast. 4 of them are hiring now, with 10+ open roles. Among them are SECQAI, Cybsafe and Mindgard.
All Cybersecurity Companies in the UK
Designs memory-safe semiconductors with post-quantum cryptography for securing servers, edge devices and critical infrastructure against both current and quantum-era threats.
Adaptive human risk management platform that uses behavioral science and data to detect and reduce cybersecurity risks caused by employee behavior.
Automated AI red teaming and security testing. First company to apply dynamic application security testing methodology to AI systems.
Integrated risk management and analytics company focused on managing digital vulnerabilities inherent in third-party ecosystems. CyDesk platform uses AI and machine learning to automatically evaluate risks from over 900 data sources for cybersecurity, compliance, and business risk management.
UK leader in AI safety, security, and assurance providing testing, evaluation, and monitoring of AI systems. Works with UK Government's AI Safety Institute and Ministry of Defence to identify AI vulnerabilities and enable safe AI deployment in critical defence environments.
Develops OT and industrial control system cybersecurity products including Dot (asset discovery), Care (risk assessment) and Optics (pre-incident threat vector analysis) for critical national infrastructure operators. Spun out of Cardiff University research and selected for the AWS European Defence Accelerator.
Multi-use technology company developing closed-source intelligence systems and threat detection platforms, focusing on OSINT capabilities and situational awareness solutions.
Cybersecurity company that provides physical network disconnection technology through the FireBreak platform, enabling remote control of network connectivity without using the internet for ultimate protection against cyber threats.
Leading exposed data intelligence platform with Gen AI Agents for threat detection that continuously monitors for exposed data and provides high fidelity intelligence for cybersecurity risk management.
Builds AI-powered airport and national infrastructure security screening products including Deeper Scan electronic-device validation and NexuSec natural-language CCTV search. Developed Deeper Scan with £80,000 DASA funding and Dstl technical support.
Award-winning quantum technology spinout from Oxford University developing quantum random number generators (QRNGs) that provide verifiably secure random numbers for cybersecurity applications.
London cybersecurity company building AI models for reverse engineering and binary analysis to verify compiled software, firmware and third-party artifacts for defence and enterprise teams.
Incident modelling consultancy building CBRN hazard, cyber attack, and disease dispersion simulation platforms for UK MoD, Dstl, and government agencies. Ploughshare spin-out commercialising Dstl research.
Roke builds defence and security technologies across AI, autonomy, cyber, secure communications and electromagnetic-spectrum operations.
Hardware-based ultra-low-latency encryption for data in motion, including the SAFE Series delivering 200 Gbps full duplex throughput and post-quantum crypto-agility. Raised £7.5M Series A in 2025 and supplies government, critical infrastructure, and telecom networks.
Cybersecurity spinout of the Exsel Group that licensed Dstl data-centric security research, commercialising Bastion — software that embeds encryption into each document so files remain secure even if the network is breached.
Belfast-based sovereign AI company building Collective, a modular AI operating system deployable on air-gapped, edge and on-prem infrastructure. Raised £10M Series A in 2025 and is one of only four SMEs holding an MoD enterprise agreement.
