Best SMS Marketing Agencies for Shopify Brands (2026): 11 Checked Against Postscript, Attentive and Klaviyo

For Shopify brands in 2026, the best SMS marketing agencies we found are Duh Retention and BS&Co, both listed at Platinum in Postscript’s partner directory; The Email Experience, at Attentive’s top Signature tier; Flowium, Lilo Social and Underground Ecom, all at Elite Master in Klaviyo’s directory; and Atelier Commerce, Stimulate, YOCTO and Enchant. Each directory listing was read on 28 October 2026; everything else here comes from the agencies’ own sites.

This guide is ours, and Retention Control sits at number one. It runs SMS for Shopify brands inside its higher retainer, but it has no listing in Postscript’s or Attentive’s partner directories, which its entry states plainly. If you want agencies judged on every retention channel rather than texting alone, read our ecommerce retention agency comparison.

SMS has fewer specialist agencies than email. By our count, Postscript’s agency directory listed 23 agencies on 28 October 2026: 4 at Platinum, 8 at Gold and 11 with Certified status only. Attentive’s directory listed 57, across its Signature, Premier and Select tiers. Klaviyo’s directory listed 674 service partners, but it has no SMS-specific tier, so a Klaviyo badge tells you about the agency’s Klaviyo work as a whole.

• Eleven agencies: Retention Control, seven based in the US, two in London and one in Cyprus.
• Listings come from the SMS platforms’ own directories, not from badges on agency websites; one mismatch is flagged below.
• Prices: seven of the eleven publish a figure, from about $2,000 to $12,000 a month.
• Disclosure: we run Retention Control. It claims no Postscript or Attentive tier, and the table shows that.

The 11 agencies side by side

What an SMS agency handles that an email agency may not

Texting has its own rules, and they decide whether a program can run at all. In the US, marketing texts sent by automated systems need the subscriber’s prior express written consent under the Telephone Consumer Protection Act, and federal rules limit telephone solicitations to the hours between 8 a.m. and 9 p.m. where the recipient lives. Some states go further: Florida and Oklahoma cut the evening limit to 8 p.m. In the UK, texting falls under PECR and GDPR instead.

The numbers themselves need approval too. US carriers require brands to register the numbers they text from, through 10DLC registration for local numbers or verification for toll-free ones, and the SMS platform runs that process. A good agency handles the consent wording on your sign-up forms, the quiet hours in every flow and the registration, before it writes a single campaign. Our SMS consent definition covers the basics, and our guide to SMS and email flows explains which messages belong on which channel.

When an SMS agency is the right hire

• Your email is working and SMS is not. If email already earns its share and texting is a list of blasts, a specialist pays for itself on flows alone.
• You are choosing between Postscript, Attentive and Klaviyo SMS. Agencies that work across platforms can tell you what each costs at your list size before you sign a platform contract.
• You are moving SMS platforms. Subscriber consent records have to move with the list. Ask how the agency has handled it before.

If you want SMS and email from one team, check the agency’s Klaviyo work too: our Klaviyo agencies guide checks every tier in Klaviyo’s own directory.

The 11 best SMS marketing agencies for Shopify brands

1. Retention Control: best for $2M+ brands adding SMS to their email retainer

Retention Control is a retention-only agency for Shopify and DTC brands. It builds and runs email and SMS flows and campaigns on Klaviyo, Omnisend, Brevo and Attentive, and publishes two retainers on its pricing page: $3,500 a month for brands doing $500K to $2M a year, which covers email, and $5,500 a month above $2M, which adds SMS, testing and loyalty design. Both start with a free 60-minute audit of the account, and the retainer runs month to month after a 90-day build.

What to know: Retention Control has no listing in Postscript’s or Attentive’s partner directories and claims no SMS tier. It does not yet publish an SMS client result either. If a platform listing or a published SMS case study is your first requirement, start with the agencies below.

2. Duh Retention: best for Shopify brands above $200K a month that want a full pod

Duh Retention is listed at Platinum, Certified in Postscript’s directory, which gives its base as Santa Clara, California. It works only on Shopify: “We’re a marketing agency that works solely with Shopify e-commerce brands.” (Duh Retention). Its homepage lists “Unlimited SMS” in its retainer and assigns each client “A dedicated 5-person Retention pod.” (Duh Retention).

What to know: it publishes its price: “One-time projects start at $2,500 while retainers run between $5,000 and $12,000 per month.” (Duh Retention). It also states a minimum: “For ongoing services, we don’t take on any brand doing less than $200,000/mo in Shopify revenue.” (Duh Retention). Onboarding runs three months, then the service rolls month to month. Its named SMS result is for MUD\WTR: “-32% 6 Month Churn (YoY) 2X SMS Subscriber Growth” (Duh Retention).

3. BS&Co: best for smaller Shopify and Klaviyo brands

BS&Co is listed at Platinum in Postscript’s directory and at Gold Master in Klaviyo’s. It describes its SMS service as “Fully integrated with email and built out the same way” (BS&Co), and its homepage sums up the work as “Email, SMS, direct mail, CRO.” (BS&Co).

What to know: it publishes the lowest entry price in this guide: a fully managed plan at $2,024 a month (BS&Co). After a trial month, clients commit for six months. Roughly ten people run the agency from Portland, Oregon, and it says its work for Billy Reid drove “Over $1,000,000 in revenue driven through additional flows launched and even more from campaigns.” (BS&Co), a figure for flows and campaigns together rather than SMS alone.

4. The Email Experience: best for in-house teams that want campaign support

The Email Experience, also known as E/X, is listed at Signature, the top tier in Attentive’s directory, which gives its base as Miami, Florida. It frames its work as “Email and SMS, read together at a resolution your team can’t get from the inside.” (The Email Experience).

What to know: it prices by service rather than by retainer. Campaign management across email and SMS is “$2,500 / per month” (The Email Experience), and flow builds are “$600 / per journey” (The Email Experience). It says “No long-term contracts, and you own everything we create.” (The Email Experience). It suits a brand with its own marketer more than one that wants the whole channel run for it.

5. Flowium: best for Klaviyo or Attentive brands on month-to-month terms

Flowium is listed at Select in Attentive’s directory and at Elite Master in Klaviyo’s. Its SMS page says “Our SMS marketing agency manages every aspect of your text promotions.” and “We will manage your SMS content calendar, integrating it into your email and social strategies.” (Flowium).

What to know: no price is published; Flowium quotes after a call. Contracts are month to month with a 60-day notice period (Flowium). Its BFCM case study for Alen reports “particularly increased repeat customer revenue (+164% over the previous account management!)” (Flowium). Attentive’s listing gives its base as Staten Island, New York.

6. Lilo Social: best if you want paid acquisition and retention from one team

Lilo Social is listed as Certified in Postscript’s directory and at Elite Master in Klaviyo’s. It calls itself “The Leading Full-Funnel E-commerce Growth Agency” (Lilo Social) and runs email and SMS alongside paid media, with a team of more than 50 (Lilo Social).

What to know: pricing is not published. Its SMS service is part of a wider retention team of strategist, copywriter, designer, project manager and developer. Its homepage case study for SEEQ reports “5X Increase in SMS Revenue” (Lilo Social) after a rebuild of every core flow. It is based in Brooklyn, New York.

7. Atelier Commerce: best for large catalogs and mixed DTC and B2B

Atelier Commerce is listed as Certified in Postscript’s directory and at Gold Master in Klaviyo’s. It says “Atelier Commerce is a retention marketing agency in New York.” and plans “Email and SMS as one program with one message hierarchy, so the channels stop duplicating each other.” (Atelier Commerce).

What to know: “We work in Klaviyo, Attentive, Postscript, and Yotpo, on Shopify and Shopify Plus and BigCommerce” (Atelier Commerce), and it names complex catalogs, subscriptions and wholesale accounts among the setups it handles. It publishes no price. One success story reports “owned revenue up 91 percent” (Atelier Commerce) for Alicia Adams Alpaca.

8. Stimulate: best for $100K+ a month brands still choosing a platform

Stimulate is listed at Gold Master in Klaviyo’s directory and does not appear in Postscript’s or Attentive’s. It says “We support leading SMS platforms like Klaviyo, Postscript, and Attentive.” (Stimulate), and its SMS page states “We work best with brands generating $100k+/month in online sales that are ready to scale using targeted, high-converting SMS strategies.” (Stimulate).

What to know: its FAQ says “Our pricing starts at $4,500/month and includes everything needed to run and grow your retention marketing program” (Stimulate), while a comparison table on its homepage shows $4k a month, so ask which applies. Terms are either monthly or a six-month contract, and each account gets two dedicated experts. It reports that for Nursing Queen “Within the first 90 days, email and SMS grew from 30.3% to 59.5% of total store revenue.” (Stimulate). It is based in St. Petersburg, Florida.

9. YOCTO: best for subscription brands on Klaviyo SMS

YOCTO is listed at Elite Master in Klaviyo’s directory and runs SMS inside Klaviyo only. Its SMS page says “We build and run SMS programs for ecommerce and subscription brands – the automated flows, segmented campaigns, and compliance that turn your list into recurring revenue.” (YOCTO).

What to know: its pricing guide lists a plan at “4,500/mo 12 campaigns a month.” without a currency symbol, and states “Month to month, with 10% off for 6 months and 15% off for 12. Requires Klaviyo and Klaviyo SMS.” (YOCTO). Confirm the currency before you compare it. It names Loop, Recharge, Skio and Smartrr among the subscription tools it works with, and reports “Mira +252% Email & SMS-attributed revenue on a subscription program.” (YOCTO). It is a small team in Nicosia, Cyprus.

10. Underground Ecom: best for UK and EU brands adding WhatsApp

Underground Ecom is listed at Elite Master in Klaviyo’s directory and is based in London. It says “The same pod runs email, SMS, and WhatsApp.” and lists “Deliverability and compliance setup, including GDPR and PECR for UK lists, and TCPA where US lists are involved.” (Underground Ecom).

What to know: each account gets a CRM director, a CRM manager, designers and copywriters, and the agency gives its size as “120+ Team Members” (Underground Ecom). It publishes no price. It names AG1, Huda Beauty, Oh Polly and Osprey among its retention clients, and says it was named Klaviyo’s agency partner of the year for EMEA in 2025 (Underground Ecom).

11. Enchant: best for CRM teams that want a fixed subscription

Enchant is listed at Platinum Master in Klaviyo’s directory and is headquartered in London, with offices in Cambridge, Berlin and New York. It says “Our SMS marketing services include strategy, setup, and ongoing optimisation, all baked into our service plans” (Enchant).

What to know: “With plans starting from £3,895, we offer award-winning CRM and email marketing expertise for various budgets.” (Enchant). The page does not say whether that is monthly. Its pricing page adds “The pricing shown in our pricing tables is based on a 12-month agreement. Shorter agreements are available for all plans, but they are more expensive.” (Enchant), and managed campaign sends cost extra. It works across 14 industries, not only ecommerce, so ask for Shopify examples.

Where a site’s claim and a directory listing differ

Badges get renewed or lost, and websites are slow to catch up. On 28 October 2026 one agency’s own page claimed a higher tier than its directory listing showed. Treat it as a question to raise, not a verdict on the work:

• Stimulate says “As a certified Klaviyo Platinum Partner, we get early access to new features” (Stimulate); Klaviyo’s directory lists it at Gold Master.

How we chose these agencies

We read every listing in Postscript’s and Attentive’s agency directories on 28 October 2026 and looked up each candidate in Klaviyo’s directory. Everything else is taken from each agency’s site; best-of lists and review sites only supplied names to check.

We kept agencies whose own sites describe ongoing SMS management for ecommerce brands and show Shopify work. We left out generalist agencies with little SMS detail on their own site, one agency whose site looked unmaintained, sites whose text would not load for checking, an agency that serves software companies rather than stores, and two agencies whose SMS pages still carried template placeholder text when we checked. Listings and prices move, so re-open each directory link before signing anything.

What to ask an SMS agency on the first call

1. Which SMS platform directories list you, and at what tier? Open the Postscript, Attentive or Klaviyo listing together.
2. How do you collect and store consent? Ask to see the sign-up wording and where the consent record lives.
3. How do you handle quiet hours and state rules? The answer should be specific to where your customers live.
4. What share of revenue comes from SMS flows versus campaigns? A specialist should show the split from the platform’s own report.
5. What will the platform cost on top of your fee? SMS platforms bill you for messages separately, and the bill grows with your list.

Final thoughts

Check the listing in the SMS platform’s own directory, then judge the agency on what a badge cannot show: how it handles consent, what it costs, the terms, and SMS results from brands your size. Postscript and Attentive specialists suit brands committed to those platforms; the Klaviyo-led agencies suit brands that want SMS inside the same tool as their email.