Best Google Ads Agency for Ecommerce - How to Choose

Five questions every ecommerce founder should ask a Google Ads agency

1. 01

   How do you charge - fixed fee, percentage of spend, or hybrid?

   A percentage of spend incentivises the agency to grow your budget regardless of your margins. A fixed fee removes that conflict. If the answer is “we’ll figure it out,” walk away.

2. 02

   What’s the longest contract you’ve signed?

   Long lock-ins (12 months, 24 months) reward agencies that can’t keep clients on outcomes alone. A 3-month initial engagement followed by rolling notice is the honest model.

3. 03

   What metric do you optimise to - ROAS, POAS, or something else?

   ROAS measures revenue per pound spent. POAS measures profit. A 5× ROAS on a 20% margin product breaks even at best. An agency that can’t articulate why this matters will scale your spend on the wrong SKUs.

4. 04

   Who actually runs my account day to day?

   Strategists pitch, but juniors execute at most agencies. Ask for the name, seniority, and tenure of the person who will be in your account every week. If they rotate every six months, your account loses memory every six months.

5. 05

   What happens if results drop in the first 60 days?

   A good agency explains its mitigation plan: parallel audits, gradual rollouts, daily monitoring. A weak agency says “results take time.” Both can be true. The honest one tells you which.

The three types of agency serving UK ecommerce

Best Agencies for Google Shopping Ads

Best agencies for Google Shopping ads — the profit-driven evaluator

"Best Google Shopping agency" is the wrong question if it's asked on awards, client logos or headline ROAS. Most comparison pieces rank agencies on signals that don't tell you whether they can protect margin, engineer Performance Max, or scale spend without destroying contribution profit. The better question is which agency can consistently turn your ad spend into profitable, scalable growth on Shopping and PMax — and that requires a profit-led framework, not a vanity scorecard.

Seven criteria for shortlisting a Google Shopping agency

1. 01

   Profit measurement built in

   Can they show sample reports with POAS, gross profit and margin tiers — not just ROAS and CPA? Do they have a documented process for ingesting your margin and cost data?

2. 02

   Profit-tiered campaign architecture

   Campaigns separated by margin tier (A/B/C), distinct profit roles (acquisition, volume, retention, clearance), and different bidding rules per tier. If the whole catalogue sits inside one or two PMax campaigns on a single global ROAS target, you already have your answer.

3. 03

   PMax engineering credentials

   Signal-based PMax setups, offline conversions, value rules and customer lists, plus a testing roadmap across asset groups, audiences and budget distribution — not 'PMax is a black box, we just trust it'.

4. 04

   Feed architecture and custom labels

   A schema for custom_label_0–4 that encodes margin, lifecycle role and price band, standardised title and product_type rules, and examples of feed work across categories and markets. Feed quality is the single highest-leverage Google Shopping asset.

5. 05

   SKU-level decision-making

   Real anonymised examples where they cut a high-revenue SKU because POAS was weak, scaled a high-margin SKU whose ROAS looked average, or moved products between tiers as margin changed. If they can't talk SKU-level, they're optimising at the wrong altitude.

6. 06

   Testing discipline

   A documented testing calendar with hypotheses (X to improve Y over Z), running across feed, structure, bidding, creative and audiences — not just tweaking budgets.

7. 07

   Reporting executives can actually use

   Page one of the monthly pack shows profit, POAS and contribution by campaign — with Keep / Kill / Scale recommendations and commercial context. A pretty dashboard with no decisions attached is a warning sign.

Worked example — "great" ROAS, weak profit

A simplified scenario from a DTC catalogue brand that moved from ROAS-led to profit-led Shopping and PMax. The pattern is more common than most founders realise.

ROAS fell on paper, but the P&L finally looked like growth instead of an expensive hobby. That swap — revenue down, profit up — is the single most reliable signal a Shopping agency is operating commercially rather than cosmetically.

Red flags your current Shopping agency is burning profit

• ROAS is 'great' but gross profit in your P&L is flat or falling
• Your Shopping or PMax setup is one or two campaigns covering the whole catalogue
• They've never asked for SKU-level margin or inventory data
• Monthly reports show clicks, impressions and ROAS — never POAS, contribution or incremental new-customer revenue
• Every case study on their site headlines ROAS, never profit
• You can't see how much budget goes to high-margin heroes vs low-margin vanity SKUs vs clearance

For named Shopping-first specialists we'd send you to instead of us when we're not the right fit — see "Who to talk to instead of us" below. For the metric itself, see the POAS reference and the full POAS vs MER vs ROAS guide.

What to do next

The best next step depends on where you are. If you’re early in evaluating agencies, read the five questions above and use them as a scorecard across the shortlist. If you’re closer to a decision and want a sanity check on your current account, book a free Profit Audit - we’ll dig into feed quality, SKU profitability, and wasted spend, and give you a written report whether or not you work with us. If your current account is in active trouble - inherited mess, suspension, performance collapse - account recovery is a different engagement model with its own 45-day playbook.