How to Set Up Conversion Events in GA4 (Step-by-Step)

Setting up a conversion event in GA4 means creating the event, marking it as a key event so GA4 treats it as something worth optimizing toward, and then confirming Google Ads can actually see it.

The terminology trips people up more than the process does — GA4 renamed “conversions” to “key events,” and both terms still show up depending on which screen you're looking at.

The short version: decide what a real conversion is on your site, create or confirm the event that captures it in GA4, mark that event as a key event, verify it's firing correctly in real-time reports, then link Google Ads to your GA4 property and import the key event as a Google Ads conversion.

Key Takeaways

What “Key Events” Means in GA4 (and Why the Old Name Still Comes Up)

GA4 used to call these “conversions.” Google renamed the concept to “key events” to be clearer about what's actually being marked — a key event is any GA4 event you've flagged as representing something valuable to your business, not a specific technical event type.

Both terms are still in circulation. Some admin screens, older documentation, and even parts of the Google Ads interface still say “conversion” when referring to what GA4 now calls a key event. They mean the same thing — this guide uses “key event” since that's GA4's current terminology.

Before You Start: What You Need

You'll need edit access to the GA4 property (to create and mark events), a clear idea of what action actually counts as a conversion on your site, and — if this event needs to reach Google Ads — admin access to link the two accounts.

If you haven't set up Google Ads' own conversion tracking yet, that's a separate, parallel piece — see How to Set Up Google Ads Conversion Tracking With Google Tag Manager for that half of the setup.

Step 1: Decide What Counts as a Real Conversion

Before touching GA4, get specific about what you're actually measuring — a completed purchase, a submitted quote form, a booked call. GA4 already automatically collects some events (page views, scrolls, outbound clicks), but a real conversion is usually a specific action those automatic events don't capture on their own.

This step gets skipped more than any other, and it's the reason so many GA4 setups end up with the wrong event marked as a key event later on.

Step 2: Create the Event in GA4

If an existing GA4 event already captures the action (for example, a form_submit event firing site-wide), you may not need a new one. If it doesn't, create a custom event — see Custom events for how event names, parameters, and collection limits work.

Custom event names have specific rules — they must start with a letter and use only letters, numbers, and underscores. Keep the name specific enough to be unambiguous later, when you're looking at a list of every event GA4 is tracking.

Step 3: Mark the Event as a Key Event

In GA4, go to Admin > Events, find the event, and toggle it on as a key event — see About key events for how GA4 defines and reports on them.

Only mark events that genuinely represent a valuable outcome. A key event list cluttered with page views or scroll-depth events dilutes the signal for anything downstream that relies on it, including Google Ads.

Step 4: Confirm the Event Is Firing Correctly

Use GA4's Realtime report to trigger the action yourself and confirm the event appears with the right name and parameters. This is the GA4 equivalent of testing in GTM Preview mode before publishing — skipping it is how a misconfigured event goes unnoticed for weeks.

If the event doesn't appear in Realtime, the key event toggle has nothing to report on yet — fix the event itself before assuming the key event marking is the problem.

Step 5: Link Google Ads to Pull In the Key Event

GA4 and Google Ads don't share data automatically. In GA4, go to Admin > Product links > Google Ads links and connect the accounts — see Connect Google Ads to Google Analytics for the current linking flow.

Google's own documentation notes data can take up to 48 hours to fully appear after linking — that delay is expected, not a sign the link failed.

Step 6: Import the Key Event as a Google Ads Conversion

Once linked, go to Google Ads' conversion actions and import the GA4 key event as a new conversion source. This is what actually makes the key event usable for Smart Bidding — linking the accounts alone doesn't import anything automatically.

Give it a moment to start reporting real data, then treat verifying it the same way you would any other Google Ads conversion action — confirm a real conversion actually shows up, not just that the import succeeded.

Common GA4 Event Setup Mistakes

Most GA4 event setups that cause downstream confusion trace back to one of these three.

Marking Every Event as a Key Event

Treating page views, scrolls, or every click as a key event buries the one or two events that actually represent revenue, making it harder for both GA4 reporting and Google Ads' imported conversions to mean anything specific.

Using Automatically Collected Events Without Checking Accuracy

GA4's automatically collected events are a convenient starting point, not a guarantee of accuracy for your specific site. An automatically collected “generate_lead” event, for example, may not match how your business actually defines a lead.

Forgetting the 48-Hour Data Delay

Assuming a Google Ads link is broken because data isn't showing up immediately is one of the most common false alarms in this whole process — give it the documented window before troubleshooting further.

How This Connects to Your Google Ads Tracking

A correctly marked GA4 key event, once imported into Google Ads, becomes a conversion action Smart Bidding can use — the same conversion action that a direct GTM-based setup would create, just arriving through GA4 instead.

Once both are running, don't expect GA4 and Google Ads to report identical numbers — they rarely do, and that's normal. For how to tell an expected gap from a real tracking problem, see GA4 vs. Google Ads Conversions: Why the Numbers Never Match.

Quick Reference: GA4 Key Event Setup Checklist

Sources and Further Reading

Google Analytics Help — Custom events

Google Analytics Help — About key events

Google Analytics Help — Connect Google Ads to Google Analytics