Company lists · Data refreshed September 2026
Top 25 Cybersecurity defense companies based in the United Kingdom
There are 1,147 cybersecurity defense companies headquartered in the United Kingdom (RevenueBase, September 2026). RevenueBase tracks 23,499 professional contacts across them, including 10,280 with verified work emails and 2,970 with mobile numbers. London is the largest hub.
This list covers cybersecurity defense companies headquartered in the United Kingdom, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Every row shows the company's own description, how directly it supports the match, and when it was last checked. Data refreshed September 1, 2026.
The 25 largest cybersecurity defense companies based in the United Kingdom
Ranked by team size| # | Company | Verified emails |
|---|---|---|
| 1 | “Sophos is a cybersecurity leader defending organizations globally with an AI-driven platform and expert-led services.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 2,711 |
| 2 | “Darktrace is a global leader in AI cybersecurity, providing the essential cybersecurity platform to secure organizations today and for an ever-changing future.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 1,791 |
| 3 | “ZeroFox is the solution to discover, validate, and disrupt external cyber threats before they harm revenue or reputation.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 382 |
| 4 | “SISA is a global forensics-driven cybersecurity solutions company, trusted by leading organizations for securing their businesses with robust preventive, detective, and corrective…” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 253 |
| 5 | “At Roke, we stand at the forefront of defence and security, delivering cutting-edge intelligence and engineering solutions that protect nations, troops, borders, and businesses.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 410 |
| 6 | “Everfox delivers trusted connectivity to protect the world's most critical environments, safeguarding the sensitive information behind decision advantage.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 13 |
| 7 | “MASS, part of the Cohort plc group, helps you realise the value of your data.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 203 |
| 8 | “WithSecure™ is Europe's cybersecurity partner of choice.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 329 |
| 9 | “Bridewell is the trusted cyber security partner for organisations operating within Critical National Infrastructure (CNI), as well as companies who want the highest standard of…” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 189 |
| 10 | “At Quorum Cyber, we're on a mission to help good people win.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 177 |
| 11 | “The Redesign Group is a global technology and cybersecurity consulting firm leveraging design thinking, interdependent subject matter expertise, and emerging technology solutions…” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 140 |
| 12 | “Ensuring your business is handling cyber security risks effectively has never been more important.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 62 |
| 13 | “Exclusive Networks is a global trusted cybersecurity specialist for digital infrastructure helping to drive the transition to a totally trusted digital future for all people and…” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 118 |
| 14 | “At Cyberfort we are passionate about the cyber security services we deliver for our customers which keeps their people, data, systems and technology infrastructure secure…” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 88 |
| 15 | “CyberSec Consulting, headquartered in the UAE and serving the iMETA market, is a distinguished professional Cyber Security and Consulting services company.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 76 |
| 16 | “CCL Solutions Group is one of Europe’s leading digital forensics, digital investigation and cyber security specialists, supporting law enforcement, government agencies, military…” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 68 |
| 17 | “At Cipher, we're redefining digital security as the premier cybersecurity leader in the Middle East.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 50 |
| 18 | “Bulletproof is now part of WorkNest Secure.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 75 |
| 19 | “As the world becomes more connected, our lives and businesses are more vulnerable.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 67 |
| 20 | “As an independent IT security specialist, Caretower provide comprehensive solutions to individual problems, thus allowing our recommendations to be unbiased.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 12 |
| 21 | “CyberOne is a Microsoft Security Elite Partner and one of only 100 global Microsoft partners recognised with Microsoft-Verified Managed XDR solution status.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 39 |
| 22 | “CyberGuard Technologies is the security division of Wavenet.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 58 |
| 23 | CybersmartPartial evidence “Cybersecurity should be simple.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 55 |
| 24 | “At Reliance Cyber, we believe in truly partnering with our customers.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 47 |
| 25 | “For over 20 years, TDI’s one and only passion has been delivering cybersecurity solutions to effectively manage the business of cyber.” Source: company website · checked Sep 1, 2026Thanks. The Data Team will review it. | 39 |
Showing 25 of 1,147 cybersecurity defense companies based in the United Kingdom
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Cybersecurity defense companies based in the United Kingdom at a glance
As of Sep 1, 2026Companies by employee count
Cybersecurity defense companies by metro
| Metro | Companies |
|---|---|
| Cybersecurity defense companies in London | 487 |
| Cybersecurity defense companies in Manchester | 42 |
| Cybersecurity defense companies in Cheltenham | 23 |
| Cybersecurity defense companies in Birmingham | 22 |
| Cybersecurity defense companies in Cambridge | 14 |
| Cybersecurity defense companies in Bristol | 13 |
| Cybersecurity defense companies in Edinburgh | 12 |
How this list was built
Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among cybersecurity defense companies, so some rows will be adjacent to the category rather than pure plays. The description and evidence rating on every row are there so you can check each match yourself.
- Source
- The RevenueBase company graph: 21.3 million companies and 398.9 million professional contacts resolved from primary sources.
- What qualifies
- Companies headquartered in the United Kingdom whose own description of what they do matches “cybersecurity defense companies”. Matching reads each company's description, not its industry code or its name.
- What we exclude
- Companies whose own description does not clearly place them among cybersecurity defense companies, and records with no verified work email. Companies headquartered outside United Kingdom are excluded even when they keep an office there.
- Match quality
- In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and an evidence rating so you can judge each match yourself.
- Ranking
- Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
- Verification
- Every listed company carries at least one verified work email, 10,280 across the full list. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
- Refresh
- This page's figures were pulled from the company graph on September 1, 2026. Lists refresh periodically as the graph is re-checked.
- Corrections
- Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.
Frequently asked
How many cybersecurity defense companies are there based in the United Kingdom?
There are 1,147 cybersecurity defense companies headquartered in the United Kingdom as of September 2026 (RevenueBase).
What is the largest company on this list?
Sophos, headquartered in Abingdon, tops this list with the largest team on record.
Which city has the most cybersecurity defense companies?
London leads with 487 headquartered companies, followed by Manchester (42) and Cheltenham (23).
How do I get contact information for these companies?
A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 10,280 verified decision-maker contacts tracked across these 1,147 companies.
How current is this list?
The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 1, 2026.
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About this data
RevenueBase is a B2B contact data platform. Its company graph covers 21.3 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph, the same data that powers RevenueBase's B2B data products and the free research portal.
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