Company lists · Data refreshed September 2026
Top 25 Sem agencies based in the United Kingdom
RevenueBase identified 1,758 sem agencies headquartered in the United Kingdom as of September 2026 and tracks 11,451 professional contacts across them, including 2,215 with verified work emails. London is the largest hub.
This list covers sem agencies 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, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed September 22, 2026.
Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.
The 25 largest sem agencies based in the United Kingdom
Ranked by team size| # | Company | Contacts | |||
|---|---|---|---|---|---|
| 1 | 123 contacts → | ||||
Indirect evidence “Adthena is the market-leading, AI-driven search intelligence platform that helps enterprise brands and agencies lower paid search costs, protect brand equity and stay ahead of…” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 2 | 104 contacts → | ||||
Indirect evidence “We're Found, the Everysearch™ agency.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 3 | 98 contacts → | ||||
Indirect evidence “The SEO Works are an award-winning provider of search marketing, websites and paid social for leading brands and prospering SME’s.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 4 | 77 contacts → | ||||
Indirect evidence “At MediaVision, we believe there's potential hidden in every search.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 5 | 73 contacts → | ||||
Strong evidence “Leading Web Design Agency In the UK and US offering top-notch SEO, SEM, SMO, PPC, Web Design, and Development services worldwide.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 6 | 69 contacts → | ||||
Indirect evidence “Unlock exceptional business growth with Mabo - an award-winning digital marketing agency specialist in paid search, social media, search engine optimisation (SEO) and Amazon…” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 7 | 62 contacts → | ||||
Indirect evidence “We're experts in making marketing work harder for SMEs in any sector.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 8 | 57 contacts → | ||||
Indirect evidence “Exposure Ninja is an award-winning search marketing agency specialising in SEO, AI Search and PPC.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 9 | 55 contacts → | ||||
Indirect evidence “Click Consult, an IQVIA business, is a multi award-winning digital and search marketing agency with a focus on organic (SEO) and paid search (PPC).” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 10 | 54 contacts → | ||||
Indirect evidence Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 11 | 51 contacts → | ||||
Indirect evidence Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 12 | 48 contacts → | ||||
Indirect evidence “We're a strategic digital marketing agency specialising in Paid Search, SEO, Google Shopping, Amazon and Social.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 13 | 48 contacts → | ||||
Indirect evidence “Screaming Frog is a search marketing agency drawing on years of experience from within the world of digital marketing.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 14 | 47 contacts → | ||||
Indirect evidence “Incredible PPC and SEO results are not the exclusive rights of those with deep pockets.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 15 | 47 contacts → | ||||
Indirect evidence “Sherbet Donkey is an SEO agency built for businesses that want sustainable, long-term growth from organic search.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 16 | 46 contacts → | ||||
Indirect evidence “Every business has one thing in common, the drive to succeed.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 17 | 46 contacts → | ||||
Indirect evidence “Bringing our 10+ years of experience and knowledge of digital marketing, Digitex Technologies has now become almost synonymous with SEO, social media marketing, website building…” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 18 | 45 contacts → | ||||
Indirect evidence “Bambu is an online marketing and advertising agency based in London, working with startup and growth brands across the UK, Europe and North America, founded by two ex-WPP…” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 19 | 44 contacts → | ||||
Indirect evidence “We're Wolfenden, an independent performance marketing agency helping ambitious brands unlock sustainable growth through organic search, authority, digital PR, paid media, data and…” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 20 | 44 contacts → | ||||
Indirect evidence “KD Web is an award winning internet marketing, web design and creative agency, providing SEO, polished website design, Ecommerce and CMS systems as well as branding and graphic…” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 21 | 42 contacts → | ||||
Indirect evidence “Hello, we’re Seed, a progressive performance marketing agency rooted in Brighton and Hove, dedicated to building sustainable growth across SEO, PPC, PR, Creative and Social.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 22 | 38 contacts → | ||||
Indirect evidence “Distinctly is an independent digital marketing agency with a passion for SEO, paid media, digital PR and content.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 23 | 38 contacts → | ||||
Indirect evidence “equimedia is a UK based, independent digital marketing agency with performance at our core.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 24 | 36 contacts → | ||||
Indirect evidence “We Are Marketing Signals.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 25 | 33 contacts → | ||||
Indirect evidence “Bird UK - bird.co.uk Bird UAE - bird.ae Bird USA - bird.marketing Bird Marketing, an award-winning digital marketing agency, is a beacon of excellence in the digital landscape.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
RevenueBase Smart Search
RevenueBase Smart Search assesses information from a company’s LinkedIn profile, information supplied directly by the company, its website, and other publicly available sources. It uses that information to rate how closely the company relates to this list’s category: sem agencies. Every row carries its rating and the description the rating was read from, so each one can be checked rather than taken on trust.
- Strong evidence
- The company's own public description of its business names sem agencies.
- Partial evidence
- Its own public description names part of sem agencies, so it works in or next to the category without describing itself that way.
- Indirect evidence
- The description shown does not name sem agencies. The match rests on the rest of the company's public profile rather than the one sentence quoted here, so this is the rating to check first.
RevenueBase Smart Search is how these lists are built: RevenueBase's data engine and AI assemble the companies that match a category defined in a user's own words, so a list can be about what companies actually do rather than about whichever industry code they were filed under.
Showing 25 of 1,758 sem agencies based in the United Kingdom
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Sem agencies based in the United Kingdom at a glance
As of Sep 22, 2026Companies by employee count
Email recency for this list is measured worldwide rather than for United Kingdom, so it is reported there. Company counts and contact totals on this page are exact for United Kingdom, over 1,758 companies.
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 sem agencies, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.
- Source
- The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
- What qualifies
- Companies headquartered in the United Kingdom whose own description of what they do matches “sem agencies”. Matching reads each company's description, not its industry code or its name.
- RevenueBase Smart Search
- RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names sem agencies), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
- What we exclude
- Companies whose own description does not clearly place them among sem agencies, 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 its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
- 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, 2,215 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 22, 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.
Sem agencies by metro
Frequently asked
What is RevenueBase Smart Search?
RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names sem agencies, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.
How many sem agencies are there based in the United Kingdom?
RevenueBase identified 1,758 sem agencies headquartered in the United Kingdom as of September 2026, matched on each company's own description of what it does rather than its industry code.
What is the largest company on this list?
Adthena, headquartered in London, tops this list with the largest team on record.
Which city has the most sem agencies?
London leads with 491 headquartered companies, followed by Manchester (76) and Birmingham (47).
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 2,215 verified decision-maker contacts tracked across these 1,758 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 22, 2026.
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About this data
RevenueBase is a B2B data infrastructure company. Its company graph covers 60 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 with RevenueBase Smart Search, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.