Top marketing firms in the US, and how to build your own list of agencies

This guide is for companies that sell to marketing agencies: reporting and project software, white-label SEO and paid media, freelance and staffing marketplaces, data and ad tech vendors. It also helps brands that want a shortlist of agencies to hire. It covers the largest firms by reported revenue, how many agencies there are and where, what "top" should mean, how agencies buy, where to get names for free, and a worked example.

The largest marketing firms in the US

The biggest marketing firms are holding companies that own many agency brands. They are listed companies, so their revenue is audited and public. These figures come from each group's own full-year 2025 results.

Three things to know when you read this table:

• Omnicom now includes Interpublic. The acquisition closed on 26 November 2025, so Omnicom's 2025 revenue includes only one month of Interpublic. Expect a much larger figure for 2026.
• The currencies and measures differ. Publicis and WPP report a figure that strips out costs re-billed to clients. Publicis calls that "net revenue" and says its pass-through revenue (€2.85 billion in 2025) "represents costs that are directly re-invoiced to clients." Compare like with like before you rank them.
• Holding companies don't buy as one. Each group runs dozens of agency brands and offices, and many buying decisions sit at the brand or office level. Treat each brand as its own account.

Below the holding companies, there is no audited ranking. Revenue for private agencies isn't public, which is why most published "top agency" lists rest on the author's opinion.

How many marketing agencies there are

Census County Business Patterns counts establishments (locations) with paid employees. In 2023:

Together that's 91,122 establishments, 780,460 employees and $69.5 billion of annual payroll. Nonemployer Statistics adds 207,863 advertising, PR and related businesses with no employees, mostly freelancers.

Two limits matter. A digital agency picks its own code when it registers, so an SEO or paid social shop may sit in advertising agencies, marketing consulting, or even graphic design or web development. And the Census publishes counts, not names.

Most agencies are small:

They cluster in a few places. By our count of the county file, California has 15,279 of these establishments (17.2%), Florida 10,070, New York 7,035 and Texas 6,250. Los Angeles County alone has 5,742, Manhattan 2,513 and Orange County, California 2,255.

What "top" should mean

Decide what you're ranking before you trust a ranking. Four kinds of evidence hold up:

Partner badges are the most objective signal for performance agencies. Google requires a Partner to keep an optimization score of at least 70%, $10,000 of ad spend across managed accounts over 90 days, and at least half its account strategists certified. Premier Partners are the top 3% of participating companies in each country, set once a year. HubSpot ranks its partners Gold, Platinum, Diamond and Elite, based on the results they've achieved for clients.

Review directories need a closer read. Clutch scores "ability to deliver" out of 40 (20 for reviews, 10 for clients and experience, 10 for market presence), counts only verified reviews toward it, and says sponsorship changes the default sort order but not a firm's underlying score. So the first names on a directory page may be sponsors.

How agencies buy and who decides

Most agencies are small and run by their founders, and that shapes who you need to reach.

Three habits of agencies help you sell to them:

• They buy for clients. Media, production and some tools are bought for a client and re-billed, which is why the holding companies report pass-through costs. If your product can be charged to a client account, the approval often skips the agency's own overhead budget.
• They buy when work changes. A new client win, a lost retainer, a new service line or a burst of hiring are the moments an agency changes its tools and suppliers. Agencies announce wins on their news pages and social accounts, and careers pages show which teams are growing.
• They plan in the fourth quarter. Many clients set next year's marketing budgets late in the year, and agencies plan headcount and tools around them.

Where to build a list of marketing agencies

Use the directories to get names, then the agency's own site to qualify each one. Finding the founder, operations lead or head of paid media at each agency is the slow part at volume, and Bebop finds those contacts and researches each account in the list. The guide to building a prospect list covers the general method.

Segment before you reach out

• Discipline. Paid media, SEO, social, PR, creative, web, or full service. A reporting tool suits paid media and SEO shops; a media planning tool suits buyers.
• Size. Use the bands above. Fewer than five staff usually means a founder doing client work all day.
• Platform. Google Premier Partner, HubSpot Diamond or Elite, Shopify Plus partner. The badge tells you their stack and their scale.
• Vertical. Many agencies specialize in healthcare, B2B technology, legal, home services or ecommerce, and say so on their homepage.
• Ownership. Independent, or a brand inside a holding company with group-level procurement.

If you're an agency looking for clients rather than selling to agencies, see lead generation for marketing agencies instead.

Worked example: a reporting tool targets the Midwest

Illustrative example. The vendor and agency are fictional; the counts come from County Business Patterns 2023.

The seller: Clearmark (clearmark.example) sells white-label client reporting dashboards to agencies at an illustrative $350 a month.

1. Size the territory. Illinois has 392 advertising, PR and marketing consulting establishments with 10 to 49 employees, and Ohio has 244: 636 in all.
2. Qualify. If an illustrative 90% are separate companies rather than branch offices, that's about 572 agencies. If half run paid media or SEO for clients (they show a Google Partner badge or list those services), about 286 fit.
3. Do the arithmetic. 286 agencies at $4,200 a year is about $1.2 million of annual revenue if every one bought, which none will. A three-email sequence to the founder and the head of paid media at each, at an illustrative 4% positive reply rate per agency, gives about 11 conversations.
4. Pick the angle. A 30-person Chicago agency, Lakefront Digital (lakefront.example), announced two new ecommerce clients last month and is hiring an account manager. More clients means more monthly reports.

Subject: Monthly reports for [new client] and [new client]

Hi [first name],

Congratulations on winning [client] and [client]. Two new retainers usually means two more sets of monthly reports, and at most agencies your size someone builds them by hand.

[Product] builds them automatically in your branding, from [the platforms they use]. [Similar agency] cut report time from [before] to [after] per client.

Most agencies bill it to the client as part of reporting. Worth a 15-minute look at how it would work for [agency name]?

[Your name]
[Company, postal address]
Reply "no thanks" and I won't email again.

The email ties a public, dated event to a likely problem and answers the budget question before it's asked.

Checklist before you contact an agency

• You know its discipline, size band and main platforms.
• You've found a dated reason to write: a client win, a hire, a new service.
• You know whether it's independent or part of a holding company.
• Your offer fits a client budget, or you can show the overhead saving.
• Every email has your postal address and a working opt-out.

Common mistakes

• Trusting a ranking without a method. If the author ranks itself first, read it as an ad.
• Treating a holding company as one account. Its brands buy separately.
• Writing to agencies of five people as if they had departments. The founder reads everything and has no time.
• Pitching during month-end reporting. Many agencies spend the first days of each month on client reports.

Next step: profile your first ten agencies with the account research template, starting with discipline, size, platforms and one dated reason to write.