02 · The ranking, scored
Email / SMS lifecycleCRO / experimentationFull retention
#1 Underground Ecom
Email / SMSLondon, UK · Email/SMS lifecycle & retention · undergroundecom.com · Founded 2018
80/100
Rank #1 of 17 in the UK
Underground Ecom: London-headquartered retention agency (~100 staff) that is Klaviyo's largest Elite partner globally. Named Klaviyo Agency Partner of the Year EMEA 2025.
Why Underground Ecom ranks #1 in the UK: Leads the UK list on nearly every pillar: quantified cases (SeoulBox +287% revenue), top Klaviyo tier, evidenced RFM/LTV/testing capability, benchmarks data product and real review volume. The reference point for the category in Europe.
Score composition80 of 100 pts
Results
27/30
SeoulBox +287% revenueKlaviyo's largest Elite partner globallyAgency Partner of the Year EMEA 2025source ↗
Specialization
20/20
Klaviyo Master Elite
Data sophistication
14/20Not yet verified
Evidence found:✓segmentation / RFM+4✓structured testing+4✓attribution+2✓predictive LTV+4No public evidence:✕cross-sell / basket analysis✕CDP
Reputation
11/15
4.2/5 across 40 on Trustpilotawards and community footprintsource ↗
Track record
8/15
since 2018 (8 years)team ~90-100
#2 Get Better
Email / SMSNew entryNorth Devon, UK · Klaviyo CRM and retention for DTC · getbetter.co.uk
69/100
Rank #2 of 17 in the UK
Get Better: North Devon CRM and retention agency working almost entirely inside the Klaviyo ecosystem, one of two Klaviyo Elite Master partners in the UK. Grew from founder Rich Evans to a team of roughly 18 to 25 in three years, serving brands from $1M to $500M across the UK, US and EU.
Why Get Better ranks #2 in the UK: Top Klaviyo tier plus the deepest documented flow work in the list outside London, with PerfectTed showing flow revenue up 245% and campaign revenue up 607% month over month. The one hole is third-party proof: no Clutch, Trustpilot or Google review presence at all, so every claim traces back to its own site.
Score composition69 of 100 pts
Results
26/30
PerfectTed: flow revenue +245.63%, campaign revenue +607.61% month over month, Buy Again journeys +405.51%source ↗
Specialization
20/20
Klaviyo Elite Master
Data sophistication
10/20Not yet verified
Evidence found:✓segmentation / RFM+4✓structured testing+4✓CDP+2No public evidence:✕predictive LTV✕cross-sell / basket analysis✕attribution
Reputation
6/15
no reviews found publiclyawards and community footprint
Track record
7/15
team ~18-25
#3 ConversionWise
CRO▼ 1Bristol, UK · CRO / conversion design for Shopify DTC · conversionwise.com · Founded 2013
66/100
Rank #3 of 17 in the UK
ConversionWise: Bristol conversion-design agency (70+ team) focused on post-click optimization for Shopify DTC: landing pages, offer testing and conversion-focused design for 4,000+ brands since 2013.
Why ConversionWise ranks #3 in the UK: Unmatched scale and social proof in UK CRO (462 Trustpilot reviews at 4.9; GBP 1B+ tracked client revenue). Design-led methodology shows less deep experimentation/data evidence than research-driven CRO firms, which caps the data pillar.
Score composition66 of 100 pts
Results
28/30
4,000+ DTC brandsGBP 1B+ tracked client revenue7,500+ conversion pages since 2013source ↗
Specialization
10/20
Conversion Rate Academyteam of 70+
Data sophistication
4/20Not yet verified
Evidence found:✓structured testing+4No public evidence:✕segmentation / RFM✕predictive LTV✕cross-sell / basket analysis✕attribution✕CDP
Reputation
10/15
4.8/5 across 352 on Trustpilotawards and community footprintsource ↗
Track record
14/15
since 2013 (13 years)team 70+
#4 AWA Digital
CRO▼ 1London, UK · E-commerce CRO / experimentation · awa-digital.com · Founded 2009
64/100
Rank #4 of 17 in the UK
AWA Digital: London e-commerce CRO specialist since 2009 with offices on three continents; co-authored the bestselling Kogan Page book 'E-commerce Website Optimization'.
Why AWA Digital ranks #4 in the UK: Deep veteran track record and enterprise-grade cases (Canon Europe across 13 territories at 1,200% ROI; 2x CRO Agency of the Year). No visible review presence is the main deduction.
Score composition64 of 100 pts
Results
27/30
Canon Europe: CRO in 13 territories, 1,200% ROI2x CRO Agency of the Yearbestselling CRO booksource ↗
Specialization
17/20
2x CRO Agency of the Year
Data sophistication
6/20Not yet verified
Evidence found:✓structured testing+4✓attribution+2No public evidence:✕segmentation / RFM✕predictive LTV✕cross-sell / basket analysis✕CDP
Reputation
5/15
no reviews found publiclyawards and community footprint
Track record
9/15
since 2009 (17 years)team senior team
#5 PAASE
Email / SMS▼ 1Milton Keynes area, UK · AI/data-driven email & SMS retention · paase.co.uk · Founded 2019
63/100
Rank #5 of 17 in the UK
PAASE: Milton Keynes-area retention agency and the first Klaviyo Elite Master headquartered in EMEA, positioning around AI and predictive data-driven email/SMS.
Why PAASE ranks #5 in the UK: Top-tier specialization and genuine predictive/LTV work (Okanui +233% automated revenue), but a thin public reputation footprint - few reviews, little community presence - keeps it behind Underground Ecom.
Score composition63 of 100 pts
Results
27/30
Okanui +233% automated revenuefirst EMEA-based Klaviyo Elite Mastersource ↗
Specialization
20/20
Klaviyo Master Elite (first in EMEA)
Data sophistication
8/20Not yet verified
Evidence found:✓segmentation / RFM+4✓predictive LTV+4No public evidence:✕cross-sell / basket analysis✕structured testing✕attribution✕CDP
Reputation
3/15
no reviews found publiclyawards and community footprint
Track record
5/15
since 2019 (7 years)team unknown
#6 Magnet Monster
Email / SMS▼ 1Manchester, UK · Email/SMS/WhatsApp retention boutique · magnetmonster.com · Founded 2018
62/100
Rank #6 of 17 in the UK
Magnet Monster: Manchester email/SMS/WhatsApp retention boutique founded by Adam Kitchen; Klaviyo Master Platinum, ~150 DTC brands served, with founder-led courses and content.
Why Magnet Monster ranks #6 in the UK: Strong documented outcomes (client email to 30% of total revenue within 90 days) and a high Klaviyo tier. No third-party review presence at all - fixing that alone would lift it a band.
Score composition62 of 100 pts
Results
27/30
Stranded Hair Group: email to 30% of total revenue within 90 days~150 DTC brands servedsource ↗
Specialization
17/20
Klaviyo Master Platinum
Data sophistication
8/20Not yet verified
Evidence found:✓segmentation / RFM+4✓structured testing+4No public evidence:✕predictive LTV✕cross-sell / basket analysis✕attribution✕CDP
Reputation
2/15
no reviews found publiclyawards and community footprint
Track record
8/15
since 2018 (8 years)team boutique
#7 Blend Commerce
CRO▼ 1Stratford-upon-Avon, UK · Shopify CRO/CVO + Klaviyo retention · blendcommerce.com · Founded 2017
59/100
Rank #7 of 17 in the UK
Blend Commerce: Stratford-upon-Avon agency combining Shopify CVO (customer value optimization) with Klaviyo retention; named Global CRO Agency of the Year 2026.
Why Blend Commerce ranks #7 in the UK: The most balanced UK profile - results, RFM/testing/attribution evidence and awards all solid. A plain Klaviyo partner tier (no Master level) is what separates it from the top three.
Score composition59 of 100 pts
Results
26/30
+61% subscription sign-ups, +14% store CVRGlobal CRO Agency of the Year 2026source ↗
Specialization
10/20
Klaviyo partnerGlobal CRO Agency of the Year 2026
Data sophistication
10/20Not yet verified
Evidence found:✓segmentation / RFM+4✓structured testing+4✓attribution+2No public evidence:✕predictive LTV✕cross-sell / basket analysis✕CDP
Reputation
7/15
no reviews found publiclyawards and community footprint
Track record
6/15
since 2017 (9 years)team in-house team
#8 Enchant Agency
Email / SMS▼ 1London, UK · Email/CRM lifecycle, Klaviyo migrations · enchantagency.com · Founded 2015
57/100
Rank #8 of 17 in the UK
Enchant Agency: London email/CRM lifecycle agency founded 2014 by global email speaker Philip Storey; Klaviyo Platinum Master specializing in complex migrations and automation.
Why Enchant Agency ranks #8 in the UK: High tier, a Klaviyo Klicks award and a striking headline (client email revenue +1000% over three years), but a small volume of published, numbered case studies limits the results pillar.
Score composition57 of 100 pts
Results
19/30
Client email revenue +1000% over 3 yearsVictorinox, SealskinzKlaviyo Klicks Award 2023
Specialization
17/20
Klaviyo Master Platinum
Data sophistication
10/20Not yet verified
Evidence found:✓segmentation / RFM+4✓structured testing+4✓attribution+2No public evidence:✕predictive LTV✕cross-sell / basket analysis✕CDP
Reputation
4/15
no reviews found publiclyawards and community footprint
Track record
7/15
since 2015 (11 years)team boutique
#9 Melusine Studio
Email / SMS▼ 1London, UK · Email/SMS lifecycle for premium DTC · melusine.studio · Founded 2019
56/100
Rank #9 of 17 in the UK
Melusine Studio: Remote-first London studio (~15 people) running email/SMS lifecycle for premium DTC brands in English and French markets; clients include REFY and Daniel Wellington.
Why Melusine Studio ranks #9 in the UK: Klaviyo Platinum Master with good quantified work (+45% client turnover in a year). Young, with no review or community footprint yet - reputation is the growth area.
Score composition56 of 100 pts
Results
26/30
Client turnover +45% in a yearclients incl. REFY, Daniel Wellingtonsource ↗
Specialization
17/20
Klaviyo Master Platinum
Data sophistication
8/20Not yet verified
Evidence found:✓segmentation / RFM+4✓structured testing+4No public evidence:✕predictive LTV✕cross-sell / basket analysis✕attribution✕CDP
Reputation
0/15
no reviews found publiclyawards and community footprint
Track record
5/15
since 2019 (7 years)team ~15
#10 Converted
CROSheffield & London, UK · CRO / experimentation (D2C, subscription) · converted.co.uk
51/100
Rank #10 of 17 in the UK
Converted: Sheffield/London CRO practice for D2C, e-commerce and subscription businesses, with 15+ years of experimentation experience.
Why Converted ranks #10 in the UK: Solid quantified results (+163% visitor-to-booking conversion), but an anonymous team page, no reviews and no certifications make it hard to verify depth - transparency would move it up.
Score composition51 of 100 pts
Results
26/30
+163% visitor-to-booking conversion for London Travel Clinicsource ↗
Specialization
10/20
15+ years of CRO practice
Data sophistication
6/20Not yet verified
Evidence found:✓structured testing+4✓attribution+2No public evidence:✕segmentation / RFM✕predictive LTV✕cross-sell / basket analysis✕CDP
Reputation
0/15
no reviews found publiclyawards and community footprint
Track record
9/15
team unknown
#11 Shawfire Media
Email / SMSNew entryManchester, UK · Email/SMS retention for Shopify brands · shawfiremedia.com · Founded 2022
51/100
Rank #11 of 17 in the UK
Shawfire Media: Manchester email and SMS retention agency founded in 2022 by Jack Shaw, working with 7 and 8 figure Shopify brands in supplements, health and consumer tech. Klaviyo Gold Master partner reporting over $15m in attributable revenue across 75+ brands.
Why Shawfire Media ranks #11 in the UK: Four case studies that name the client and the number, including a channel share moving from 20% to 42% of revenue and holding above 35% for eighteen months. Credentials stop at Gold Master and there is no review profile anywhere, so the reputation pillar is carried entirely by a self-published regional award.
Score composition51 of 100 pts
Results
22/30
Dr. Shiba: email from 20% to 42% of total revenue in 90 days, held above 35% for 18 monthssource ↗
Specialization
14/20
Klaviyo Gold Master
Data sophistication
6/20Not yet verified
Evidence found:✓segmentation / RFM+4✓CDP+2No public evidence:✕predictive LTV✕cross-sell / basket analysis✕structured testing✕attribution
Reputation
3/15
no reviews found publiclyawards and community footprint
Track record
6/15
since 2022 (4 years)team ~10
#12 Proof3
CRONew entryShrewsbury, UK · Ecommerce CRO and experimentation, Magento and Shopify · proof3.co · Founded 2022
50/100
Rank #12 of 17 in the UK
Proof3: Shrewsbury based ecommerce growth agency spun out of Adobe Commerce Gold partner iWeb, running what it calls digital experience optimisation across Magento and Shopify retailers such as Autoglym, Goddiva, Tile Giant and Just Kampers.
Why Proof3 ranks #12 in the UK: Six client-named numbers including Autoglym revenue up 49% and Tile Giant conversion up 28.33%, backed by a real analytics and attribution practice. The catch is breadth: CRO sits alongside paid search, SEO and feed management, so several headline figures are not attributable to experimentation alone.
Score composition50 of 100 pts
Results
25/30
Goddiva: conversion 1.2% to 2%, AOV +185%, revenue +212%source ↗
Specialization
10/20
Adobe Gold Certified via iWebShopify PartnerGoogle Marketing Platform certified
Data sophistication
6/20Not yet verified
Evidence found:✓structured testing+4✓attribution+2No public evidence:✕segmentation / RFM✕predictive LTV✕cross-sell / basket analysis✕CDP
Reputation
2/15
no reviews found publiclyawards and community footprint
Track record
7/15
since 2022 (4 years)team 11-50
#13 ElliotDigital
Email / SMSNew entryLondon, UK · Email/SMS retention for DTC brands · elliotdigital.co.uk
49/100
Rank #13 of 17 in the UK
ElliotDigital: London email and SMS retention agency run by Elliot Scott as a small full-stack team covering strategy, copy, design and build. Klaviyo Platinum Master partner with UK DTC clients including SURREAL, Days Brewing, HUX and Cornelia James.
Why ElliotDigital ranks #13 in the UK: A high Klaviyo tier and a recognisable UK DTC client list, but only three published projects and one of them reports projected rather than realised revenue. Publishing five or six client-named results would move it past the agencies currently above it.
Score composition49 of 100 pts
Results
21/30
NU-VEL: 1344% revenue growth in a year, email at 40% of monthly revenuesource ↗
Specialization
17/20
Klaviyo Platinum Master
Data sophistication
4/20Not yet verified
Evidence found:✓segmentation / RFM+4No public evidence:✕predictive LTV✕cross-sell / basket analysis✕structured testing✕attribution✕CDP
Reputation
3/15
no reviews found publiclyawards and community footprint
Track record
4/15
team small, founder-led
#14 PM Digital
CRO▼ 2Northern Ireland (remote), UK · Shopify CRO for 7-9 figure DTC brands · www.pmdigitaldesign.com · Founded 2022
41/100
Rank #14 of 17 in the UK
PM Digital: Northern Ireland remote-first team (~16) doing Shopify CRO for 7-to-9-figure DTC brands, with an avatar/awareness-level parallel testing system and a public CRO learning hub.
Why PM Digital ranks #14 in the UK: Interesting methodology and real numbers (Ripley Rader GBP 1.5m+ revenue, +22% RPV), but credentials are self-stated and there's no third-party review presence yet.
Score composition41 of 100 pts
Results
20/30
Ripley Rader: GBP 1.5m+ revenue, +22% revenue per visitoravatar-segmented parallel testing system
Specialization
6/20
Shopify Partner (self-stated)CRO Learning Hub
Data sophistication
10/20Not yet verified
Evidence found:✓structured testing+4✓attribution+2✓segmentation / RFM+4No public evidence:✕predictive LTV✕cross-sell / basket analysis✕CDP
Reputation
2/15
no reviews found publiclyawards and community footprint
Track record
3/15
since 2022 (4 years)team ~16
#15 Browser to Buyer
CRO▼ 2London, UK · Full-service ecommerce CRO · browsertobuyer.com · Founded 2016
41/100
Rank #15 of 17 in the UK
Browser to Buyer: London full-service e-commerce CRO agency led by Dave Gowans, formerly of Conversion.com; Convert.com certified partner.
Why Browser to Buyer ranks #15 in the UK: Credible pedigree and strong claims (average +30% CVR in six months, minimum 10x ROI), but claims are aggregate and unverified - itemized case studies would substantially raise the results score.
Score composition41 of 100 pts
Results
18/30
Avg +30% CVR within 6 months, min 10x ROI claimed+GBP 1m sales in year one for a clientsource ↗
Specialization
14/20
Convert.com certified partner
Data sophistication
6/20Not yet verified
Evidence found:✓structured testing+4✓attribution+2No public evidence:✕segmentation / RFM✕predictive LTV✕cross-sell / basket analysis✕CDP
Reputation
1/15
no reviews found publiclyawards and community footprint
Track record
2/15
since 2016 (10 years)team founder-led
#16 Customers Who Click
CRO▼ 2London, UK · Performance-based CRO for ecommerce/DTC · customerswhoclick.com
36/100
Rank #16 of 17 in the UK
Customers Who Click: London performance-based CRO shop for e-commerce/DTC founded by Will Laurenson, who hosts the Customers Who Click podcast; offers a $100k revenue guarantee model.
Why Customers Who Click ranks #16 in the UK: The guarantee model and content presence are distinctive, but there is minimal verifiable evidence: no reviews, no certifications, and case results shown without client names or context.
Score composition36 of 100 pts
Results
18/30
A/B test wins of +45% and +70%$100k revenue guarantee modelCRO podcast + newslettersource ↗
Specialization
4/20
No formal certificationsworks on a performance-fee model
Data sophistication
6/20Not yet verified
Evidence found:✓structured testing+4✓attribution+2No public evidence:✕segmentation / RFM✕predictive LTV✕cross-sell / basket analysis✕CDP
Reputation
5/15
no reviews found publiclyawards and community footprint
#17 Sendfluence
Email / SMS▼ 2UK (remote), UK · Email/SMS lifecycle, performance-fee model · sendfluence.co.uk · Founded 2024
23/100
Rank #17 of 17 in the UK
Sendfluence: Small founder-led UK Klaviyo agency running email/SMS lifecycle on a performance-fee pricing model.
Why Sendfluence ranks #17 in the UK: Certified Klaviyo partner, but no published case studies, near-zero review presence and unknown track record - the least public evidence in the UK list. Claiming and documenting results would change its position quickly.
Score composition23 of 100 pts
Results
5/30
Performance-based pricing modelcertified Klaviyo expertssource ↗
Specialization
10/20
Klaviyo Partner
Data sophistication
4/20Not yet verified
Evidence found:✓segmentation / RFM+4No public evidence:✕predictive LTV✕cross-sell / basket analysis✕structured testing✕attribution✕CDP
Reputation
2/15
4.5/5 across 1 on Googleawards and community footprint
Track record
2/15
since 2024 (2 years)team small, founder-led
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