Company lists · Data refreshed September 2026
Top 25 Sem agencies based in London, United Kingdom
RevenueBase identified 491 sem agencies headquartered in London, United Kingdom as of September 2026 and tracks 3,884 professional contacts across them, including 510 with verified work emails. London is the largest hub.
This list covers sem agencies headquartered in London, 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 London, 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 | 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. | |||||
| 4 | 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. | |||||
| 5 | 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. | |||||
| 6 | 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. | |||||
| 7 | 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. | |||||
| 8 | 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. | |||||
| 9 | 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. | |||||
| 10 | 30 contacts → | ||||
Indirect evidence “Iconic Digital is a leading digital marketing agency based in London, UK.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 11 | 27 contacts → | ||||
Indirect evidence “KAU Media Group is a full service media agency that deliver compelling digital marketing solutions.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 12 | 25 contacts → | ||||
Indirect evidence “We help companies grow with revenue-driven SEO.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 13 | 19 contacts → | ||||
Indirect evidence “The GoodNet: Where performance meets responsibility.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 14 | 17 contacts → | ||||
Indirect evidence “Digital Search Group Limited is a performance driven online marketing agency built on highly knowledgeable foundations, which have grown over 16 years of providing online…” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 15 | 16 contacts → | ||||
Indirect evidence “With more ways than ever for consumers to find your brand, we make you visible wherever they’re searching, going beyond best practice to build holistic search strategies for…” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 16 | 15 contacts → | ||||
Indirect evidence “We deliver tailored digital marketing solutions to help you meet your business objectives and stay competitive in the market.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 17 | 15 contacts → | ||||
Indirect evidence “Bough Digital is a professional full-service digital marketing company based in the UK, which aims to deliver a first-class, full scale service to a variety of clients.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 18 | 14 contacts → | ||||
Indirect evidence “VM Interactive is a digital marketing agency with real passion for driving traffic.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 19 | 13 contacts → | ||||
Indirect evidence “As agencies grow, they’re often obsessed with trying to ‘own’ as much of the customer journey as possible, over time turning into broader generalists.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 20 | 13 contacts → | ||||
Indirect evidence “Award-Winning SEO Agency for $1M+ Tech Companies (SaaS, Web) and 6-figure E-Commerce Brands.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 21 | 9 contacts → | ||||
Indirect evidence “Bravada: On-Demand Marketing, is an independent digital marketing agency that supports high-end brands and ambitious businesses' growth utilising social media ads and search…” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 22 | 9 contacts → | ||||
Indirect evidence “Merj is your partner for SEO and AEO.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 23 | 9 contacts → | ||||
Indirect evidence “At Helium, we believe in no-nonsense, results-driven performance marketing.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 24 | 9 contacts → | ||||
Indirect evidence “SEO-Driven Digital Agency.” Source: RevenueBase Database · checked Sep 22, 2026Thanks. The Data Team will review it. | |||||
| 25 | 8 contacts → | ||||
Indirect evidence “Signify is an online marketing agency based in London, providing clients with multi platform marketing tailored to achieve results and help to maximise brand, ROI and customer…” 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 491 sem agencies based in London, United Kingdom
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Sem agencies based in London, United Kingdom at a glance
As of Sep 22, 2026Companies by employee count
Email recency for this list is measured across the whole United Kingdom list rather than for London, so it is reported there. Company counts and contact totals on this page are exact for London, over 491 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 London, 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 London 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, 510 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 in the United Kingdom
- Sem agencies in London491
- Sem agencies in Manchester76
- Sem agencies in Birmingham47
- Sem agencies in Leeds32
- Sem agencies in Bristol31
- Sem agencies in Nottingham31
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 London, United Kingdom?
RevenueBase identified 491 sem agencies headquartered in London, 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 510 verified decision-maker contacts tracked across these 491 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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Sem agencies by geography
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- Sem agencies based in Calgary, Canada
- Sem agencies based in Edmonton, Canada
- Sem agencies based in Montreal, Canada
- Sem agencies based in Ottawa, Canada
- Sem agencies based in Toronto, Canada
- Sem agencies based in Vancouver, Canada
- Sem agencies based in Berlin, Germany
- Sem agencies based in Hamburg, Germany
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.