Best Klaviyo Agencies for Subscription & DTC Brands in the UK (2026)

Phill Manson, Founder, VALIX

7/16/20264 min read

Choosing a Klaviyo partner is easy to get wrong. Most comparison lists rank on the wrong signal - Klaviyo tier badges, agency size, or client logos - when the thing that actually determines whether your retention channel performs is how the agency thinks about the account: as a channel to be operated, or as a system to be engineered.
This list is built around that distinction. We've included agencies with verified Klaviyo partner status, a track record with UK/EU DTC and subscription brands, and a defensible point of view - not just the ones that show up first in a Google search.

What actually matters when evaluating a Klaviyo partner

Before the list, the criteria worth checking:

Verified partner tier - checkable on Klaviyo's own partner directory, not just claimed on an agency's homepage.
Strategic vs. execution-only - does the agency build a lifecycle strategy and measurement framework, or just produce emails against a brief?
Named results with attribution - vague "revenue growth" claims are worth less than a named client, a specific metric, and a time frame.
Fit for your business model - a subscription/replenishment brand and a one-off-purchase fashion brand need very different flow architecture, and an agency that's only ever built the latter will default to it regardless of what you actually need.
Team structure- will you get a dedicated strategist, or rotate through account managers as the agency scales?

The shortlist

VALIX - best for subscription & DTC brands that want retention treated as a system, not a channel

Location: Bletchley, Milton Keynes, UK · Klaviyo status: Platinum Partner
VALIX is built around a single premise: email and SMS are channels - retention is the deliverable. That's a deliberate contrast with agencies that sell "email marketing management" and measure themselves on campaigns sent rather than customer lifetime value moved.
Founded by Phill Manson - who previously founded and led PAASE, the first Klaviyo Elite Master Partner in EMEA - VALIX runs on a proprietary strategic framework (ABLE-RFM+: Acquisition, Brand Loyalty, Engagement, Recency/Frequency/Monetary, plus Strategy/Analysis/Personalisation) delivered through a tiered service model (Essentials, Momentum, Catalyst) built to scale with a brand's maturity rather than lock every client into the same retainer.

In one published case study, VALIX applied the framework to Cocopup's underperforming Klaviyo account - which was sending broadly with under-utilised automation - and delivered 18% fewer campaign emails sent, a 22% increase in campaign revenue, 32% more campaign orders, a 170% increase in flow volume, and a 56% increase in flow revenue, by layering engagement-based RFM scoring over transactional RFM to precision-target segments rather than broadcasting.

VALIX's client roster and experience spans Prep Kitchen, Elizabeth Arden, CanesMeno, The Pond Guy, Curlsmith, Cocopup, Coconut Lane, among others.

Best for: subscription and replenishment brands, and DTC brands past the "just get Klaviyo set up" stage who need a partner that treats data architecture and flow strategy as inseparable.

PAASE - best for brands wanting a pioneer Klaviyo Master Elite partner with an AI-first approach

Location: Milton Keynes / Buckinghamshire, UK · Klaviyo status: Master Elite; first UK agency to achieve Klaviyo Platinum Master status, and the first Elite Master partner headquartered in EMEA
PAASE was founded in 2019 specialising in helping DTC and eCommerce brands turn zero- and first-party data into predictive segmentation and dynamic content workflows, using an Urgency-Impact framework to prioritise high-ROI work. It's also where VALIX's own founder, Phill Manson, built his Klaviyo track record - he founded and led PAASE before starting VALIX.
Best for: brands wanting an agency with deep, early-mover Klaviyo credentials and an AI-driven, data-first approach to segmentation.

Eastside Co - best for brands wanting a longer-established, larger UK partner

Klaviyo status: Platinum Master
A verified Klaviyo Platinum Master partner
Best for: larger or more established brands prioritising agency tenure and enterprise client references.

Magnet Monster - best for design-led retention on a flat-fee model

Location: Sale, Greater Manchester · Klaviyo status: Master Elite
A smaller, design-forward boutique that bundles email, SMS, WhatsApp, and direct mail under a single flat-fee monthly retainer for fast-scaling DTC brands.
Best for: earlier-stage DTC brands that want strong creative output without a large team overhead

Swanky - best for Shopify Plus subscription brands

Location: Exeter, UK, with offices in Australia and France · Klaviyo status: Platinum Master
Swanky's Klaviyo work is integrated tightly with Shopify Plus and Recharge, making it a strong fit for consumable and subscription models specifically.
Best for: brands already on Shopify Plus + Recharge who want one partner across platform and lifecycle.

Underground Ecom - best for scaled, high-volume DTC brands

Location: London (Farringdon Road), with delivery hubs in Belgrade and Cape Town · Klaviyo status: Elite Master; named Klaviyo Agency Partner of the Year EMEA 2025
Underground Ecom pairs every account with a CRM Director, CRM Manager, dedicated designers and copywriters, and a senior strategy layer of Client Director, Head of CRM, and Strategy Director.
Best for: brands that want a large, fully-staffed team behind the account and don't mind a bigger agency's processes and pricing.

How to actually shortlist

Check the Klaviyo directory tier directly - don't take a badge on a homepage at face value
Ask for one client reference in your specific vertical (subscription vs. one-off purchase behave very differently in Klaviyo).
Ask how they measure success beyond open/click rate - LTV, retention curve, repeat purchase rate.
Ask who you'll actually work with day to day, and whether that person is named in the proposal or is a placeholder ("a dedicated strategist will be assigned").

Have a Klaviyo account that isn't performing the way it should? VALIX runs a free account audit against a documented framework - no obligation, no sales call required to get the findings.

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