How to choose a GEO agency

Plenty of SEO agencies now sell GEO too, and their proposals tend to read alike. Hold each one to three plain tests: is it specific, can it be measured, and does it hold up over time?

Start with the question the engines ask

We asked ChatGPT, Google AI Overviews, Google AI Mode, Gemini and Perplexity “how to choose a GEO agency” 22 times between 15 and 25 September 2026. Read together, the answers make a decent buyer’s brief: they show which criteria the engines put first.

• Every platform answered with a numbered list of criteria, and the same three led each list: measurement and tracking of AI visibility, a GEO-specific methodology rather than repackaged SEO, and proof of results tied to business outcomes.
• ChatGPT’s answer ran to eight criteria and ended with a scorecard; Gemini’s opened with “evaluate their measurement and tracking capabilities”. Google’s AI Overview added a “red flags” section every time.
• Perplexity cited 13 sources per answer here, more than for any other question tested, and its stable sources were long checklists and guides. Google AI Mode cited a Reddit thread in 18 of 22 runs, so buyers who ask are shown peer experience alongside agency claims.
• The People Also Ask box asked “how to pick an SEO agency?” (21 times), “is SEO dead now with AI?” (21) and “what is the best GEO strategy?” (18). The SEO question is never far from the GEO one.

Eight criteria for choosing a GEO agency

1. Measurement you can repeat. The agency should track a fixed set of your buyer questions on each engine daily, or at least across many days, and report who is cited and named. A single check is noise: Underneath’s own data shows sources cited once in twelve runs that never appeared again, and sources cited in ten of twelve that were positions worth defending.
2. A method that is more than SEO. Ask what the agency does that an SEO agency does not. The answer should include definition-first page structure, structured data for AI engines, entity and knowledge-graph work, and building citations on the third-party pages the engines use. If the answer is “content and links”, it is an SEO agency.
3. Per-engine thinking. ChatGPT, Google’s AI surfaces and Perplexity do not share sources. In Underneath’s study of a service keyword, ChatGPT took 26 of 28 citations from outside Google’s top 10 while Google’s AI Overview reused the top 10 heavily. Across 80 buyer questions, four assistants recommended the same first pick for only 10.0% of questions. An agency that talks about “AI search” as one thing has not measured it.
4. Technical competence. Crawler access for OAI-SearchBot, PerplexityBot and Google-Extended, server-rendered text, validated schema, one canonical URL per page. Ask to see the agency’s technical GEO checklist. If the engines’ crawlers cannot fetch and read a page, none of the content work on it will be retrieved.
5. Proof, without guarantees. Ask for a client’s before-and-after measurement: questions, engines, dates, citations. Be wary of any guarantee of being cited; no agency controls the engines, and the honest ones say so.
6. A third-party plan. Ask which roundups, directories, forum threads and publications the agency intends to get you into, and how it chose them. The right answer names the pages the engines actually cite for your category, which the audit should have found.
7. Reporting tied to outcomes. Mentions and citations by engine, share of voice against named competitors, and sessions and leads from AI referrals, monthly, against a baseline. Not “AI mentions up 300%” with no denominator.
8. Fit with your stack and your team. Implementation that works on the platform you already run, a plan for training your own people, and a clear line between what is in scope and what costs extra.

A scorecard you can use on a call

Score each agency on the eight criteria from 0 to 3. An agency scoring under 2 on measurement or method should be dropped regardless of the total.

Red flags

• A guarantee of citations, or a promise of “number one in ChatGPT”. The engines change their sources without notice; in our tracking, Perplexity replaced its entire source set for one query in a single day.
• One screenshot as evidence. One answer proves nothing about the next.
• No mention of third-party sources. On Perplexity and ChatGPT, third-party pages are most of the answer.
• No technical checklist. An agency that cannot say which AI crawlers your site allows has not checked whether its content work can be retrieved.
• SEO reports with “AI” added. Rankings and traffic are SEO metrics; GEO needs mentions, citations and share of voice.
• Talk of “gaming” or “hacking” the engines. Google’s guidance for its AI features says no special optimizations are needed to appear in them, which leaves little for a hack to do.

Questions to ask before you sign

1. Which questions will you track, on which engines, how often, and can I see the baseline before we start?
2. What do you do that an SEO agency does not, and which of it happens off my site?
3. Which third-party pages will you try to get us into for our category, and how did you identify them?
4. Which AI crawlers do you allow, and how do you check that our pages render without JavaScript?
5. Show me one client’s measurement six months apart: questions, engines, dates, citations, and the leads that followed.
6. What is in the monthly report, and what is the first number you would expect to move?
7. What is in scope, what is an add-on, and what happens to the work when the engagement ends?

Agency, in-house or tool

An agency makes sense when you need the method, the third-party outreach and the measurement at once, and do not yet have someone who has run GEO end to end. In-house makes sense once you have the tracker and the writing standards and need volume rather than method. A tool alone measures visibility; it does not change it. There is also a middle route: buy the audit from an agency, run the tracker yourself, and buy the third-party work as a project. Underneath’s programs are built to hand the tracker and the standards to your team at the end.

Frequently asked questions

How do I choose a GEO agency?

Choose the agency that measures your AI visibility repeatedly on each engine, explains a method that includes page structure, structured data, entity work and third-party citations, shows dated proof, and reports mentions, citations and share of voice against a baseline. Drop any agency that guarantees citations or shows one screenshot as evidence.

How is choosing a GEO agency different from choosing an SEO agency?

The usual due diligence still applies, plus three tests: per-engine measurement, a plan for the third-party pages the engines cite, and technical checks for AI crawlers and rendering. An SEO agency can pass the usual checks and still fail all three.

What is the best GEO strategy?

There is no single tactic. What the engines reward, in our measurements, is a system: definition-first pages with question headings, complete structured data, a consistent brand entity, presence on the third-party pages each engine cites, and daily tracking to see what changed, all run and measured per engine.

How much does a GEO agency cost?

Published 2026 price guides range from about $1,500 to $50,000 a month, and WebFX (opens in a new tab) puts mid-sized companies at $5,000 to $25,000. Underneath’s programs are priced in three bands, $5,000 to $10,000, $11,000 to $20,000 and $20,000+ a month, each beginning with an audit whose fee is credited if you continue. When you compare quotes, compare the audits too: a one-off check and a repeated, per-engine audit are not the same product at any price.

How long before a GEO agency shows results?

Changes to pages that are already indexed can show up in Google AI Overviews and AI Mode within weeks, and in Perplexity once it recrawls them. Third-party citations take longer to land, usually months, and ChatGPT recommendations take longest. Ask for the first comparison against the baseline at 30 days.

Is SEO still worth it in 2026?

Yes. Ranking is still the main way into Google’s AI surfaces: in our study of 486 searches, pages ranking in the top three were cited in the AI Overview about twice as often as pages at positions 7 to 10. Ask any GEO agency how its work fits alongside your SEO, and be wary of one that proposes to replace it.