Retail media advertising: a beginner's guide for brand advertisers

Retail media is one of the fastest-growing ad channels in the UK, with online retail media reaching £1.5bn in the first half of 2025 alone (IAB UK). Retailers like Ocado, Tesco, Morrisons and Iceland offer routes into grocery audiences, while Currys, John Lewis and Deliveroo represent entirely different shopping contexts spanning electronics, homeware, cosmetics and beyond.

Through retail media, these retailers give brands the ability to reach their shopper audiences with precise, contextually relevant messaging across a growing range of channels. Here is what it is, how a campaign works, and where to start if it is new to you.

What is retail media advertising?

Retail media advertising is paid media that uses a retailer's first-party shopper data to target consumers with relevant messaging. It works across two broad environments.

• Onsite refers to placements on the retailer's own channels, including their website and app. These include sponsored product listings, search ads, banner placements and brand pages.
• Offsite extends that same retailer data into the wider digital ecosystem, reaching shoppers through display, online video, connected TV (CTV) and audio across the open web. Demand for offsite is growing fast: 46% of buyers allocated more than 41% of their digital retail media spend to off-site in 2025, yet only 30% of retailers currently offer offsite ads, creating a clear supply-side gap for brands that want cross-channel reach (IAB Europe).

Did you know?

Epsilon Retail Media pairs CitrusAd’s onsite engine with cross-channel audience recognition and activation, so brands can move the same shopper from first impression to purchase. Find out more here.

Why is retail media so important?

Three things distinguish retail media from the digital advertising most brand teams are used to:

1. First-party shopper data. With third-party cookies on the way out and GDPR keeping cross-site tracking tight, retailers hold some of the richest, most consented first-party data available. Retailers know who buys what, when, and how often, and that insight can be used to identify existing, lapsed and prospective customers with a level of precision that proxy-based targeting cannot match.
2. Responsive to how people actually shop. Modern shopping journeys span multiple touchpoints, channels and timeframes, and retail media allows brands to create relevant purchase moments across that journey rather than relying on a single interaction at a single point.
3. You can see if it worked. Because the retailer sees both the ad impression and the transaction, it is possible to connect spend to real sales outcomes, including purchases that happen in physical stores.

Why retail media is also complex

Retailers were not historically media owners. They have digitalised quickly, and many are now building media businesses at the same time as running them. The result is a landscape where every network looks and operates differently. There are now more than 200 retail media networks operating globally, with some estimates putting the figure closer to 270, and at least 28 active in the UK.

Consider the range. A business like Sainsbury's, with Argos sitting alongside its grocery operation, is a very different retail proposition to Iceland, or to a business like Wickes, which serves both trade and consumer audiences. Different customer bases, different data sets, different inventory, different commercial models. Each retailer is, quite rightly, building a media offering that reflects its own strengths and shoppers. But for brands and their agencies, who are used to buying media in more standardised ways, navigating that variation takes effort.

Fragmentation across platforms, teams, tools and measurement remains one of the biggest barriers to growth. According to IAB Europe, network fragmentation (51%) and lack of standardisation (53%) are the most significant challenges the industry faces.

Choosing the right network

The question is not simply who has the biggest reach, but whose data tells you the most about the people you want to find.

Those you sell through - The most straightforward starting point is a retailer you already sell through. You are reaching shoppers in a context where they can act on your message immediately. The data is rich, the path to purchase is short, and you can measure the full loop from impression to transaction.

Those you don't sell through - But the opportunity does not stop at the retailers that stock your products. Businesses in adjacent sectors like travel and quick service restaurants hold transaction data that can signal whether someone is in-market for what you offer.

Consider a platform like Deliveroo. If you are a drinks brand, a kitchen appliance company, or a meal kit provider, that kind of behavioural data could tell you who is in-market based on real spending patterns. This is where commerce media comes in. Commerce media takes the retail media model and expands it beyond traditional retailers, enabling any business with valuable transaction data to create media opportunities for aligned advertisers.

Whichever route you take, three things separate the networks that deliver real outcomes from the ones that simply promise impressions.

1. Unique reach. Every retailer has an audience, but the networks worth investing in have an audience you cannot easily find elsewhere and can prove it. Iceland Foods, for example, gives brands access to price-sensitive, often underrepresented consumers that other networks underserve. That distinctiveness is the first test. The second is whether the network can make that audience cleanly addressable, rather than serving impressions against inflated or modelled segments.
2. Omnichannel activation. A high-performing network should unify activation across onsite and offsite environments rather than treating them as separate buying channels. Wickes, for instance, launched its retail media network with both onsite and offsite capability from day one, allowing brands to reach its trade and consumer audiences across the retailer's own platforms and across the wider web through a single, identity-linked view of its shoppers.
3. Proven outcomes. Measurement is where strong networks truly distinguish themselves. The best can tie both online and offline transactions directly to online media impressions using closed-loop attribution Currys Connected Media, for instance, combines first-party data with identity technology to give brands a unified view of in-market tech shoppers, and recent campaigns have shown in-store sales uplifts of up to 20%.

Identity underpins all three. Without a robust identity layer connecting real people across channels, touchpoints and transactions, reach is inflated, activation is fragmented, and measurement is incomplete. Solutions like Epsilon's COREid resolve online and offline signals to real individuals, and as IDC notes, "person-level identity is key to targeting, closed-loop attribution, data, and personalised scaled activation of ads."

For a deeper look at how to evaluate networks against these criteria, read the full guide.

How to run a retail media campaign as a brand

Most retail media campaigns follow the same shape. The sequence mirrors the three pillars that underpin any successful retail media strategy: reach, activation and measurement.

Define your objective. Are you trying to drive sales, recruit new customers, or build awareness in a category? Pick one. It will shape everything else. Campaigns that try to do all three tend to do none of them well.

Build your audience. The default for many retail media networks is to target existing logged-in shoppers, which can mean you pay a premium to reach people already in your funnel. Identity-led targeting, built on deterministic data like name and address rather than just email, is what allows you to find genuinely new customers at scale.

Plan your activation. Onsite placements such as sponsored products, search ads and banners tend to drive conversion. Offsite placements across the open web, programmatic display, connected TV and audio tend to extend reach and build awareness. Most campaigns use a mix, and the strongest results come when these channels are planned together rather than activated in isolation.

Set your measurement framework. Before launch, settle which metrics matter, whether you will test for incrementality, and how in-store sales will be counted. The measurement plan should be designed to follow an impression through to a sale, both online and in store, and over a long enough window to capture higher-consideration purchases where weeks or months may separate first impression from final transaction.

Launch and optimise. Retail media data comes back quicker than most channels, and the brands that get the most from it treat the first few weeks as a live learning phase rather than a waiting period. Set objectives and efficiency guardrails up front, then let the data lead in-flight, shifting budget between placements and audiences based on real signals rather than assumptions made before launch.

When these steps fit together, the numbers can be serious. Currys ran a multi-channel campaign with Epsilon Retail Media that combined onsite retail media with connected TV and online video. It delivered a 46% conversion uplift versus display alone, 56,000 tracked in-store visits and a 3:1 return on ad spend, and went on to win Best Use of Retail Media at the Digiday Awards Europe.

Download the retail media strategy guide

If you want the longer version of how to think about reach, activation and measurement, the guide walks through each one and gives you the questions to ask any retail media partner before you commit.

Download the retail media strategy guide.