How to choose an affiliate marketing agency (and whether you need one)

UK advertisers spent £1.10 billion on affiliate marketing in 2023, according to the IAB UK and PwC Digital Adspend study (IAB UK / PwC, 2023). As the channel grows, more brands are buying specialist support, and the partner you appoint shapes everything: publisher quality, commercial terms, and whether the programme compounds or drifts. Choosing an affiliate marketing agency is therefore a decision worth slowing down for. This guide sets out what agencies actually do, how to evaluate them, the questions that reveal the most, and when a different model serves you better.

Key takeaways

• An affiliate marketing agency should cover strategy, publisher recruitment and management, tracking and optimisation, not just admin.
• Evaluate agencies on sector experience, publisher relationships, platform fluency and transparency, not on the size of their client logo wall.
• The most revealing questions concern who works on your account day to day, how performance is measured, and who owns the publisher relationships if you leave.
• Commission-only pricing sounds low risk but can reward volume over quality. Understand the incentives behind every pricing model.
• An agency is not the only route: independent consultancy or in-house management can be a better fit depending on scale and how much senior attention you need.

What an affiliate marketing agency actually does

An affiliate marketing agency is a specialist partner that plans, launches and manages affiliate programmes for brands. A capable agency brings established publisher relationships, platform expertise and commercial experience that would take years to build internally.

The work breaks down into six core services. If an agency cannot describe how it delivers each one, treat that as a signal.

Strategy is the part most often underweighted. Recruitment, creative and reporting all follow from the commercial plan: which publisher types to prioritise, how commissions should differ by partner value, and what growth is realistic. In practice, weak programmes usually trace back to a missing strategy rather than missing effort. If you want a sense of where your current programme stands, auditing your affiliate programme is the natural first step.

Agency, consultancy or in-house: which model fits?

Before comparing agencies, it is worth asking whether an agency is the right model at all. There are three realistic routes to running the channel, and each suits a different situation.

A traditional agency suits brands that want the programme fully managed and have the budget to fund a team. An independent consultancy suits brands that want senior strategic direction, a programme audit or a fractional channel leader, often working alongside an in-house marketer or an incumbent agency. In-house management suits large programmes where the channel justifies dedicated headcount, usually supported by external expertise at key moments. EngageMore's Growth consultancy sits in the second camp: senior-only, commercially focused and structured around the engagement you need rather than a fixed retainer.

The honest answer is that no model is universally best. What matters is the seniority of the people doing the thinking and how directly they are accountable for results.

What to look for when choosing an affiliate marketing agency

Once you have decided an agency is the right model, six factors separate strong candidates from weak ones.

1. Experience and track record. Look for evidence of results in programmes like yours: real numbers, named clients where possible, and outcomes over time rather than launch-month spikes. A portfolio of documented case studies is worth more than any pitch deck.
2. Sector expertise. Publisher mixes, commission norms and seasonality differ sharply between retail, finance, travel and subscription. An agency that knows your sector starts with a map; one that does not will learn at your expense.
3. Publisher relationships. Ask how the agency finds, vets and manages publishers, and which partner types it knows best. Depth matters more than volume: a genuine relationship with the right cashback, content and comparison partners beats a spreadsheet of ten thousand contacts.
4. Platform and tools fluency. The agency should know your tracking platform, or the one it recommends, inside out: reporting, attribution settings, validation processes and recruitment tools. Technology fluency is what turns data into decisions.
5. Communication and transparency. You should know what is being done, why, and what it is delivering, without chasing. Regular reporting, honest commentary on what is not working, and named points of contact are the baseline.
6. Commercial alignment. Understand how the agency makes money and whether that incentivises the outcomes you want. A model that rewards gross sales volume can quietly favour discount-heavy activity over profitable growth.

How to research and shortlist agencies

A structured shortlist process protects you from choosing on chemistry alone.

1. Gather candidates. Ask industry peers, your network or platform contacts, and publishers you rate. Recommendations from people who see agencies perform from the other side of the programme are especially valuable.
2. Review their work. Read case studies, client lists and commentary on each agency's site. Look for evidence of thinking, not just activity.
3. Hold first conversations. Brief each shortlisted agency properly and judge the quality of the questions they ask you. Good agencies interrogate your goals before proposing anything.
4. Take references. Speak to one current and one former client. Ask what the agency is like in month nine, not month one.
5. Compare proposals on substance. Judge the proposed strategy, the named team and the measurement plan. Discount anything that could have been written without reading your brief.

Questions to ask before you sign

The interview stage is where the real differences surface. These questions do the most work:

• Who will actually work on our account? Pitches are often led by senior people who then disappear. Ask for the named team, their experience and how much time is allocated to you each week.
• How do you recruit and vet publishers? Listen for a process: sourcing, quality criteria, brand fit and compliance checks, not just access to a network directory.
• How do you measure success? Strong answers cover incrementality and profitability, not just last-click revenue. Ask what they would report in a bad month.
• How do you optimise a live programme? Commission structures, publisher mix, placement testing and seasonal planning should all feature. Vague answers here predict a programme that plateaus.
• What does your fee include, and what sits outside it? Confirm whether network fees, platform costs, placement budgets and creative work are included or additional.
• Who owns the accounts and relationships if we part ways? Network and platform accounts should be held in your name, with publisher relationships documented. This single question prevents the most painful exits.

Pricing models and contract terms

Agencies typically price in one of three ways. A flat monthly fee buys predictability and suits defined scopes. A performance commission, usually a percentage of affiliate-driven revenue, aligns the agency with growth but can reward volume over quality if left uncapped. A hybrid model combines a lower base fee with a performance element, and is the most common structure for established programmes.

Whichever model you choose, the contract should nail down four things: payment terms, an initial term with a fair notice period, the KPIs against which performance is judged, and ownership. Insist that tracking platform and network accounts sit in your company's name. In our experience, brands that skip this clause discover the cost only when they try to leave.

Shorter initial terms with clear review points beat long lock-ins. An agency confident in its work does not need a two-year contract to keep you.

Making the partnership work

The agencies that perform best are the ones given the clearest brief. Set specific goals and KPIs at the start, agree a reporting rhythm, and hold a proper quarterly review that looks at strategy rather than just numbers. Share what is happening inside the business: product launches, stock issues and pricing changes all affect what publishers can deliver.

Then measure what matters. A well-run affiliate programme should show incremental revenue and healthy blended margins, and it should complement your other marketing channels rather than cannibalise them. If reporting only ever shows last-click revenue going up, ask harder questions.

The EngageMore verdict

Most guides to choosing an affiliate marketing agency quietly assume the agency model is the destination. It is not. The real question is where the senior thinking sits and who is accountable when the numbers land. Plenty of agencies deliver genuine expertise; plenty of brands also pay agency prices for a junior account executive and a monthly spreadsheet. The evaluation process in this guide exists to tell those two outcomes apart before you sign, not after.

Our position is straightforward: judge every option, including EngageMore, on the seniority of the people doing the work and their willingness to be measured on results. If you want an experienced view on whether your programme needs an agency, a consultant or a rethink, book a strategy call and we will tell you honestly which model fits.