How to Connect Shopify to Klaviyo (UK Guide)

If you run a Shopify store and want email and SMS marketing that reflects what customers actually do, Klaviyo is the usual choice, and connecting the two is genuinely straightforward. The native integration does the heavy lifting: it pulls your customers, orders, products and on-site behaviour into Klaviyo automatically, then keeps them in sync. The honest headline is that for the large majority of UK stores the native integration is all you need, and reaching for custom code first is a mistake.

This guide covers the setup, what actually syncs, the flows worth building, and the part most guides skip: getting marketing consent right under UK GDPR and PECR, so you are not building a polished email programme on an unlawful list.

The short answer

Install the Klaviyo app from the Shopify App Store, authorise the connection, and Klaviyo begins syncing your store data within minutes. Then:

1. Get consent handling right first. Make sure email and SMS marketing consent flows from Shopify into Klaviyo correctly (see the consent section below).
2. Confirm the Klaviyo on-site snippet is in place (the native integration usually injects it) so browsing, product views and add-to-cart events are tracked.
3. Turn on the core flows — abandoned cart, welcome, post-purchase and winback.

No middleware, no Zapier, no custom build is required for any of this. You only need custom events or server-side work in specific cases, covered at the end.

Setting up the native integration

The Klaviyo integration is a one-time install:

• In Shopify, go to the App Store, search for Klaviyo, and install it (or start in Klaviyo and connect Shopify from Integrations).
• Authorise the requested scopes. Klaviyo needs read access to customers, orders and products, plus permission to add its on-site tracking.
• Confirm the on-site tracking snippet is installed. On modern Shopify themes the native integration handles this; on a heavily customised or headless theme you may need to add Klaviyo's klaviyo.js manually.

Once authorised, Klaviyo backfills your historical data (customers and recent orders) and then keeps everything current. There is nothing to schedule or maintain.

What actually syncs

It helps to know exactly what crosses the connection, because your flows and segments depend on it:

Data	What comes across	Used for
Customers / profiles	Email, name, location, marketing consent status, order history	Segmentation, suppression, list hygiene
Orders	Placed Order, Ordered Product, Fulfilled Order, Cancelled Order and Refunded Order events, with line items and value	Post-purchase flows, revenue reporting, RFM segments
Catalogue	Product feed — titles, images, prices, URLs, variants	Product blocks, recommendations, back-in-stock
On-site events	Active on Site, Viewed Product, Added to Cart, Started Checkout	Abandoned browse and abandoned cart flows
Checkout / cart	Started Checkout, with cart contents	The abandoned cart flow's trigger

The combination of order events and on-site events is what makes Klaviyo worth using over Shopify's built-in email: you can trigger on behaviour, not just on purchases.

One UK note on value. Klaviyo records order totals as they come from Shopify, which are VAT-inclusive for UK stores. If you report Klaviyo's attributed revenue alongside your accounts, remember you are comparing a gross (VAT-inclusive) figure to net figures elsewhere.

The flows worth building first

Klaviyo's value is in automated, behaviour-triggered flows. Start with these four:

• Welcome series — triggered when someone subscribes (via a signup form or at checkout). Introduce the brand, set expectations, and often include a first-order incentive.
• Abandoned cart / abandoned checkout — triggered by Started Checkout, and typically the single highest-revenue flow. Pull in the actual cart contents using the catalogue feed.
• Post-purchase — triggered by Placed Order. Thank the customer, set delivery expectations, request reviews, and cross-sell complementary products after a sensible delay.
• Winback — triggered when a customer crosses an inactivity threshold (for example, no purchase in 90–180 days, tuned to your typical reorder cycle).

A practical sequencing tip: build suppression and exclusion logic into every flow from day one. Exclude people who have since purchased from the abandoned cart flow, and exclude recent buyers from winback. Flows that ignore this annoy customers and push up unsubscribes.

Data and consent: getting GDPR and PECR right

This is the part that carries real legal weight in the UK, and the integration will not do it for you.

Marketing email and SMS to consumers in the UK are governed by PECR (the Privacy and Electronic Communications Regulations) on top of UK GDPR. The core rule: you generally need explicit, opt-in consent to send marketing emails and texts to individuals. In practice:

• Do not auto-subscribe at checkout. Shopify lets a customer place an order without opting into marketing. Only customers who actively tick a clearly labelled, unticked marketing opt-in should sync to Klaviyo as subscribed. Klaviyo respects Shopify's consent flag, so the job is making sure your Shopify checkout captures consent properly — never pre-ticked.
• Treat email and SMS consent separately. Consenting to emails is not consent to texts. Capture and store them as distinct permissions; Klaviyo supports separate email and SMS consent states.
• The "soft opt-in" exists but is narrow. PECR allows marketing to existing customers about similar products without fresh consent, if you collected the address during a sale and gave a clear opt-out at that point and in every message. Many stores rely on this; if you do, document that you meet every condition, and never extend it to SMS or to people who only browsed.
• Honour unsubscribes and erasure. Every message needs a working unsubscribe, and you must be able to action data deletion requests. Klaviyo and Shopify both expose suppression and data-removal tools. Use Klaviyo's suppression list rather than deleting profiles outright, so you do not accidentally re-import someone who opted out.

A clean, consent-aware list will usually outperform a far larger but legally shaky one, both on deliverability and on risk. If your consent capture is messy, or your two systems disagree on who is subscribed, that is a data integration problem worth fixing before you scale sending.

When you need custom events or server-side tracking

The native integration covers customers, orders, catalogue and standard on-site behaviour. You only need to go beyond it when:

• You have behaviour Shopify does not emit — quiz completions, loyalty tier changes, subscription (recurring order) lifecycle events, wishlist adds, or back-in-stock interest. These need custom events pushed to Klaviyo via its API or client-side track calls.
• You run a headless or heavily customised storefront where the standard snippet does not fire reliably. Here you may track events server-side through Klaviyo's API for accuracy.
• Accuracy matters more than convenience. Ad blockers and consent tools can suppress client-side tracking, so high-value events such as Placed Order are best sent server-side from your backend or a webhook.
• You are stitching Klaviyo to other systems — a separate subscriptions platform, a loyalty app, or your ERP — so customer state stays consistent everywhere. That is a classic API integration job.

If you find yourself reaching for these, scope tightly. Add the one or two custom events you genuinely need, rather than rebuilding what the native integration already does well.

Common gotchas

• Double opt-in vs single opt-in. Klaviyo can require a confirmation click before subscribing. Single opt-in grows your list faster; double opt-in gives stronger consent evidence and cleaner deliverability. For UK B2C, single opt-in with a clear, logged consent action is usually defensible — but choose deliberately.
• Historic customers without consent. When Klaviyo backfills, do not assume old customers are subscribed. Map their consent status honestly; importing them as subscribed without a basis is a PECR breach.
• Duplicate profiles from guest checkouts using different emails. Keep an eye on profile counts and merge where Klaviyo allows.
• Discount-code and review-app events often need a separate integration. Check whether your apps have native Klaviyo support before assuming events will appear.

A note on cost

The Klaviyo integration is free to install; you pay for your Klaviyo plan, which is priced on active profile count and sending volume. Any third-party app or development costs are separate and depend entirely on your stack. Treat any figures you see quoted online as indicative UK market ranges rather than firm prices — the right answer depends on your list size, your storefront, and how much you do natively versus custom.

How APIwise can help

For most UK Shopify stores the native Klaviyo integration is the right answer, and you will not need us to install it. Where we add value is the bits that are easy to get wrong: making sure consent flows correctly between Shopify and Klaviyo under GDPR and PECR, adding reliable server-side or custom events for headless and subscription stores, and keeping Klaviyo in sync with the rest of your stack. If you want a senior, vendor-neutral pair of eyes before you scale your sending, our fixed-price Integration Health Check will tell you exactly what is solid and what needs fixing. Get in touch.