A media buyer is the person responsible for where ad spend goes. They set up campaigns, manage budgets, adjust bids, and decide which audiences see which ads. On a performance marketing team, they own the ad account.
The term comes from traditional advertising, where buying media meant negotiating placements on TV, radio, and in print. In digital advertising, the job is different but the core responsibility is the same: spend money on attention, and make sure the return justifies it.
What a media buyer actually does
Day to day, a media buyer on a Facebook or Meta campaign is doing a few things. They're setting up campaign structure: which objective, which audiences, which placements. They're monitoring performance metrics: cost per click, cost per purchase, return on ad spend. They're adjusting budgets toward what's working and pulling spend from what isn't. And they're testing, mostly audience segments and bidding strategies.
What they're not doing, usually, is writing copy or designing visuals. That's the creative team's job. The media buyer takes creative assets and decides how to distribute them. They're working in the ad account, not in a design tool.
Media buyer vs creative director
These two roles get conflated constantly, especially on small teams where one person does both. But they're solving different problems.
The creative director asks: what should this ad say and look like to make someone stop and care? The media buyer asks: who should see this ad, when, at what bid, and for how long?
The split matters because the skills don't overlap much. A strong media buyer is comfortable with spreadsheets, bid mechanics, and audience architecture. A strong creative director thinks in hooks, angles, and emotional responses. When one person does both jobs, they're usually weaker at one of them.
For a deeper breakdown of where each role actually has leverage on campaign performance, the media buying vs creative breakdown is worth reading.
On small ecommerce teams
Most small Shopify brands don't have a dedicated media buyer. The founder, or a generalist marketer, runs the ad account alongside everything else. That's fine, but it means the media-buying function is often underdeveloped: budgets stay flat instead of scaling winners, audience testing is inconsistent, and decisions get made on instinct rather than data.
The two things that tend to help most at this stage are a cleaner campaign structure (fewer, tighter ad sets rather than dozens of small ones) and competitor research as an input for decisions. If three competitors are running the same offer angle for six weeks, that's a signal the market is responding. That affects what you buy and who you target, not just what you produce.
What competitor ad data tells a media buyer
Media buyers at larger brands watch the Meta Ad Library regularly. Ads that keep running are usually profitable. Ads that disappear after a few days are probably not working. Tracking this over time gives you a rough read on what's resonating in your category before you spend on your own tests.
Spreshapp does this tracking automatically. You can save competitor ads to a swipe file, watch which ones stay active over weeks, and use that as an input when planning campaigns. It doesn't replace proper testing, but it makes the starting point smarter.