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Company lists · Data refreshed September 2026

Top 25 Online advertising agencies based in London, United Kingdom

Compiled by the RevenueBase Data Team Data refreshed Sep 5, 2026 2,404 companies tracked

RevenueBase identified 2,404 online advertising agencies headquartered in London, United Kingdom as of September 2026 and tracks 18,802 professional contacts across them, including 2,308 with verified work emails. London is the largest hub.

This list covers online advertising 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, how directly it supports the match, and when it was last checked. Data refreshed September 5, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase SmartSearch, 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.

How to read this list HQ checked on every row Match evidence on every row Refreshed Sep 5, 2026 86% judged on-target in blind review
2,404Companies
18,802Contacts tracked
2,308Verified emails
Unlock all 2,404 companies Free signup · no credit card · 500 free credits

The 25 largest online advertising agencies based in London, United Kingdom

Ranked by team size
Top 25 of 2,404 online advertising agencies based in London, United Kingdom, ranked by team size, largest first. Data refreshed Sep 5, 2026. Evidence rates how directly each company's own description names online advertising agencies: strong (names it), partial (names part of it), indirect (matched on its full profile rather than the summary shown). Click a count to unlock that company's people.
#CompanyHeadquartersEmployeesContacts
1
M C Saatchi PerformanceIndirect evidence
London, United KingdomHQ checked Sep 5, 2026201-500457

“We are a Global digital media agency specializing in taking a human approach to connecting brands with people across all channels.”

Source: company website · checked Sep 5, 2026
2
BIG GroupIndirect evidence
London, United KingdomHQ checked Sep 5, 202651-200177

“Founded in 1991, with offices in Amsterdam, Bath, Dubai and London our award-winning employee-owned company has consistently ranked as one of the UK's leading independent digital…”

Source: company website · checked Sep 5, 2026
3
Investis DigitalIndirect evidence
London, United KingdomHQ checked Sep 5, 2026501-1,000158

“IDX (formerly Investis Digital) specializes in elevating companies and brands and maximizing technology to build strong, relatable, and authentic connections with their audiences.”

Source: company website · checked Sep 5, 2026
4
E IntelligenceIndirect evidence
London, United KingdomHQ checked Sep 5, 202651-200117

“e intelligence is a renowned global leader in the digital marketing space.”

Source: company website · checked Sep 5, 2026
5
FOUNDIndirect evidence
London, United KingdomHQ checked Sep 5, 202651-200104

“We're Found, the Everysearch™ agency.”

Source: company website · checked Sep 5, 2026
6
FinixioIndirect evidence
London, United KingdomHQ checked Sep 5, 202651-20096

“Finixio is UK based remote first Marketing & SEO Agency helping clients all over the world.”

Source: company website · checked Sep 5, 2026
7
The Media PeopleIndirect evidence
London, United KingdomHQ checked Sep 5, 202611-5083

“Powered by our people, our campaigns put your audience first.”

Source: company website · checked Sep 5, 2026
8
Social BoostIndirect evidence
London, United KingdomHQ checked Sep 5, 202651-20079

“Social Boost has helped to grow more than 25 million real Followers, created content for 100+ brands, and generated over 300k sales leads.”

Source: company website · checked Sep 5, 2026
9
Mind Digital GroupIndirect evidence
London, United KingdomHQ checked Sep 5, 202651-20076

“Mind Digital Group is an independent digital company that is focused on servicing global clients and partner agencies.”

Source: company website · checked Sep 5, 2026
10
GA AgencyPartial evidence
London, United KingdomHQ checked Sep 5, 202651-20070

“GA Agency is an award-winning digital marketing agency helping brands all over the world grow their business and revenue in the online space.”

Source: company website · checked Sep 5, 2026
11
ClickscoIndirect evidence
London, United KingdomHQ checked Sep 5, 202651-20066

“As a new chapter in our Digital Agency begins, we are also a fantastic place to work, with a reputation for discovering and nurturing some of the finest minds in the business…”

Source: company website · checked Sep 5, 2026
12
Eureka DigitalIndirect evidence
London, United KingdomHQ checked Sep 5, 202651-20065

“Eureka Digital is a multi-award-winning digital marketing agency specializing in healthcare and pharmaceuticals.”

Source: company website · checked Sep 5, 2026
13
77agencyIndirect evidence
London, United KingdomHQ checked Sep 5, 202651-20064

“We are an award-winning full-service digital agency, part of Jakala group with 1,800 employees across 16 countries around the world.”

Source: company website · checked Sep 5, 2026
14
OCM Digital MediaPartial evidence
London, United KingdomHQ checked Sep 5, 202651-20054

“OCM is a leading adtech agency providing solutions to advertisers, advertising agencies and to web, mobile & video publishers.”

Source: company website · checked Sep 5, 2026
15
Stellar SearchIndirect evidence
London, United KingdomHQ checked Sep 5, 202611-5048

“We're a strategic digital marketing agency specialising in Paid Search, SEO, Google Shopping, Amazon and Social.”

Source: company website · checked Sep 5, 2026
16
Harvest DigitalIndirect evidence
London, United KingdomHQ checked Sep 5, 202611-5048

“We are a leading independent digital media agency.”

Source: company website · checked Sep 5, 2026
17
Digitex TechnologiesIndirect evidence
London, United KingdomHQ checked Sep 5, 202651-20046

“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: company website · checked Sep 5, 2026
18
BAMBUStrong evidence
London, United KingdomHQ checked Sep 5, 2026n/a45

“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: company website · checked Sep 5, 2026
19
Beautiful DigitalIndirect evidence
London, United KingdomHQ checked Sep 5, 202611-5044

“Beautiful Digital is a full service digital marketing agency.”

Source: company website · checked Sep 5, 2026
20
PropellerIndirect evidence
London, United KingdomHQ checked Sep 5, 202611-5044

“We’re a digital agency delivering stand-out experiences that generate results.”

Source: company website · checked Sep 5, 2026
21
DianomiPartial evidence
London, United KingdomHQ checked Sep 5, 202611-5040

“Dianomi™ is the leader in premium native advertising for the financial services, technology, corporate and lifestyle sectors.”

Source: company website · checked Sep 5, 2026
22
KinaseIndirect evidence
London, United KingdomHQ checked Sep 5, 202611-5039

“Kinase is a leading Digital Marketing Agency providing services to some of the UK’s top companies.”

Source: company website · checked Sep 5, 2026
23
DistinctlyIndirect evidence
London, United KingdomHQ checked Sep 5, 202611-5038

“Distinctly is an independent digital marketing agency with a passion for SEO, paid media, digital PR and content.”

Source: company website · checked Sep 5, 2026
24
Cynosure DesignsIndirect evidence
London, United KingdomHQ checked Sep 5, 202611-5036

“Cynosure Designs is a UK & UAE-based IT and marketing agency providing 360° digital solutions that are experience-driven and results-focused.”

Source: company website · checked Sep 5, 2026
25
Haarty HanksIndirect evidence
London, United KingdomHQ checked Sep 5, 202611-5035

“Haarty Hanks is a digital marketing agency comprised of tech nerds, creative designers and innovative strategists that plan and execute exceptional brand communications and web…”

Source: company website · checked Sep 5, 2026

Showing 25 of 2,404 online advertising agencies based in London, United Kingdom

See the full list, filter by size, metro and specialty, and get verified emails and direct dials for all 2,308 reachable decision-makers.

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Online advertising agencies based in London, United Kingdom at a glance

As of Sep 5, 2026
1-10Median size (employees)
LondonLargest hub · 2404 HQs
Contacts with mobile numbers
Sep 5, 2026Data refreshed

Companies by employee count

1-10
1,624
11-50
646
51-200
108
201-500
10
501-1,000
6
1,001-5,000
3
5,001-10,000
2
10001+
1

Email recency for this list is measured across the whole United Kingdom list rather than this city, so it is reported there. Company counts and contact totals on this page are exact for London, over 2,404 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 online advertising agencies, 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: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase SmartSearch, 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 “online advertising agencies”. 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 online advertising 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 an evidence 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, 2,308 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 5, 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.

Online advertising agencies by metro in the United Kingdom

Frequently asked

How many online advertising agencies are there based in London, United Kingdom?

RevenueBase identified 2,404 online advertising 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?

M C Saatchi Performance, headquartered in London, tops this list with the largest team on record.

Which city has the most online advertising agencies?

London leads with 2404 headquartered companies, followed by Manchester (310) and Birmingham (201).

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 2,308 verified decision-maker contacts tracked across these 2,404 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 5, 2026.

Ready to reach these companies? Verified emails and direct dials for all 2,404 online advertising agencies based in London, United Kingdom. Start with a free account, no credit card.

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Related lists

Browse: Companies home · Online advertising agencies in United Kingdom · All United Kingdom lists · All Online advertising agencies lists · New lists

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 SmartSearch, 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.

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