Klaviyo and Shopify: The Integration Guide

What the native integration actually does

Klaviyo's Shopify integration is a first-party connection, not a third-party bridge, which is why it is the most reliable data source you can give your email platform. Once connected, it does three big jobs: it syncs your product catalogue, it streams customer and order events in real time, and it backfills historical data so your segments are populated from the moment you switch on.

That combination is what lets Klaviyo do things a generic email tool cannot: trigger flows on real store behaviour, personalise emails with live product data, and segment on actual purchase history rather than guesswork. Get the integration right and everything downstream gets easier. Get it wrong and every flow inherits the gaps.

The events that power your flows

The integration sends Shopify behaviour into Klaviyo as metrics, and these events are the triggers your flows fire on. The ones that matter most:

• Placed Order. Fires when a customer completes a purchase. It powers post-purchase flows, order and shipping notifications, customer lifetime value calculations and purchase-based segments.
• Checkout Started. Fires when a shopper reaches checkout with an email captured. This is the high-intent trigger for your abandoned cart flow, and the one you should recover on.
• Viewed Product. Fires when someone views a product page. It drives browse abandonment and lets you personalise around what a subscriber actually looked at.
• Added to Cart. Fires when an item goes into the cart. Useful as a secondary signal, though Checkout Started is the higher-intent event to build recovery on.
• Ordered Product and Fulfilled Order. Item-level and fulfilment events that let you build replenishment timing, review requests and cross-sell logic.

Understanding which event does what is the difference between a flow that fires at the right moment and one that misses. The strategic ordering of these flows is covered in our ecommerce email automation guide.

Catalogue sync, back-in-stock and on-site tracking

Catalogue sync

The integration imports your Shopify products into a Klaviyo catalogue: images, prices, URLs and variants. That catalogue is what powers dynamic product blocks, personalised recommendations and the automatic product imagery in cart and browse emails. If the sync is broken or stale, your emails show wrong prices or missing images, which quietly erodes trust and conversions.

Back-in-stock alerts

Back-in-stock is one of the highest-converting flows Shopify brands can run, and it depends entirely on the integration. When inventory for a variant returns above zero, Klaviyo can trigger an alert to everyone who subscribed to that product. It recovers demand you would otherwise lose to a sold-out page, but only if the catalogue and inventory sync are healthy.

On-site tracking

Klaviyo's on-site tracking, the Active on Site and Viewed Product behaviour, comes from a small snippet Shopify adds through the integration. On newer Shopify themes this is largely handled for you, but it is worth verifying, because without it your browse abandonment and on-site personalisation have nothing to work with.

Forms, discount codes and sign-up

The integration also underpins how you grow and reward your list.

• Sign-up forms. Klaviyo forms embed directly on your Shopify storefront to capture email and SMS, feed the welcome flow and grow the list. Building high-converting forms is a topic in its own right, covered in our guide to Klaviyo sign-up forms.
• Discount codes. Klaviyo can generate unique Shopify discount codes inside a flow or campaign, so each subscriber gets a single-use code rather than a shared one. This protects margin and lets you track redemption, but it relies on the Shopify connection being authorised correctly.
• Coupon and price rule sync. For the codes to work, Klaviyo needs the right Shopify permissions. A partial reconnect after a theme or app change is a common reason codes suddenly stop generating.

Common breakages and how to catch them

The integration rarely fails loudly. It degrades, and the symptoms show up as revenue quietly going missing. The ones we find most often:

• Events not syncing after a replatform or theme change. A new theme or a headless build can break on-site tracking, so Viewed Product and Active on Site stop firing and browse abandonment goes silent.
• Checkout Started not populating. If checkout events are missing, your abandoned cart flow has nothing to trigger on, and cart recovery drops to zero without an obvious error.
• Stale or partial catalogue. Products missing from the Klaviyo catalogue mean broken images and wrong prices in dynamic blocks.
• Discount codes failing to generate. Usually a permissions or reconnection issue after an app or theme update.
• Duplicate or missing profiles. Customers created outside the normal checkout, through some third-party apps, can arrive with inconsistent consent or identifiers.

The way to catch these is to check the integration's metrics regularly: are Placed Order, Checkout Started and Viewed Product all still counting in the last 24 hours? A flat line on any of them is your early warning. This kind of monitoring is part of what we cover in a Klaviyo audit, because a broken integration makes every other fix pointless.

Getting the integration right the first time

Connecting Klaviyo to Shopify takes minutes. Configuring it so every flow, form and personalised block has clean, complete data underneath it is the part that separates an email programme that earns from one that leaks. The catalogue has to sync, the events have to fire, the forms have to embed, the codes have to generate and on-site tracking has to be live, and all of it has to survive the next theme update.

This is foundational work we set up and monitor for the brands we run Klaviyo for. For Eternal Collagen, a clean Shopify and Klaviyo setup sat underneath the six flows that drove an extra £90k in email revenue in four months while the list grew from around 500 to over 11,000 subscribers. If your integration was connected once and never checked since, have us audit and rebuild it, or start with a £499 Klaviyo audit and we will tell you exactly which events are firing and which are quietly costing you sales.