Best Klaviyo Agencies in 2025

Email marketing drives more revenue for eCommerce brands than almost any other channel — and Klaviyo is the engine most serious brands trust to do it. But Klaviyo is only as powerful as the team running it. A well-configured account with tight segmentation, smart flows, and disciplined campaign strategy can account for 30–50% of a store's total revenue. A poorly managed one bleeds money and deliverability.

That's the real reason choosing the right Klaviyo agency matters. It's not just about outsourcing emails — it's about handing someone the keys to one of your highest-leverage revenue channels.

The problem? There are hundreds of agencies and freelancers claiming Klaviyo expertise. Some are exceptional. Many are generalist digital marketing shops that treat Klaviyo as an afterthought. A few will actively hurt your account by blasting unsegmented lists until your deliverability collapses.

This guide cuts through the noise. We've reviewed the Klaviyo partner ecosystem to highlight agencies that are genuinely worth your time — and give you the framework to evaluate any agency before you sign a contract.

Want to skip ahead? Browse the full vetted list at KlaviyoDirectory.com/directory.

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What to Look for in a Klaviyo Agency

Before we get to names, here's what separates a great Klaviyo agency from a mediocre one.

1. Klaviyo Master Certification (and Platinum Partner Status)

Klaviyo's partner tiers — Silver, Gold, Platinum — are based on client revenue managed, not just headcount. An agency at the Platinum level has processed serious volume through the platform. More importantly, look for staff who hold individual Klaviyo Master Certifications, which require passing exams on flows, segmentation, deliverability, and analytics. It's a baseline signal that they actually know the platform, not just the buzzwords.

2. Genuine eCommerce Email Marketing Experience

Klaviyo is purpose-built for eCommerce, but that doesn't mean every agency using it understands eCommerce. You want an agency that's worked with brands in your category — whether that's fashion, supplements, home goods, or DTC food. They should be able to reference specific challenges like abandoned cart recovery rates, post-purchase LTV strategy, and how to structure flows for subscription vs. one-time purchase products.

Ask for case studies. Real ones, with revenue numbers or percentage lifts — not vague testimonials.

3. Flow Architecture Expertise

Automated flows are where the money lives. A well-built welcome series, abandoned cart sequence, post-purchase flow, and win-back campaign running 24/7 will outperform any campaign calendar. The best Klaviyo experts don't just set up the default flows — they build them around your specific customer journey, with conditional splits based on purchase history, product category, and engagement level.

Ask any prospective agency: What does your typical abandoned cart flow look like? If they describe a single email, find someone else.

4. Deliverability Management

This is the unglamorous side of Klaviyo email marketing that separates professionals from amateurs. Good agencies actively manage list hygiene, monitor spam complaint rates, warm new sending domains properly, and know when to suppress unengaged subscribers before they damage your sender reputation. Poor deliverability means your campaigns land in spam — and you often won't notice until the damage is done.

5. Pricing Model Transparency

Klaviyo agencies typically charge one of three ways: a flat monthly retainer, a percentage of email-attributed revenue, or an hourly rate. Each model has tradeoffs. Flat retainers are predictable but can misalign incentives if the agency isn't motivated to grow your revenue. Revenue share aligns incentives but can get expensive fast. Whatever the model, get clarity upfront on what's included — how many campaigns per month, who owns the copy, what reporting looks like, and what the exit terms are.

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Top Klaviyo Agencies in 2025

These are some of the strongest agencies you'll find in the Klaviyo partner ecosystem. Each has a distinct positioning — use this as a starting point, not a final ranking. Your ideal agency depends on your stage, category, and budget.

For the full list with filters by specialty and pricing, visit klaviyodirectory.com/directory.

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1. Flowium

Flowium is one of the most recognized pure-play Klaviyo agencies in the market. They work exclusively with eCommerce brands and have built a significant portion of their business around Klaviyo strategy, flows, and campaigns. Their team is large enough to handle enterprise-level accounts but maintains a specialist focus. They publish extensively on Klaviyo best practices, which signals genuine depth — not just execution.

Best for: Mid-market to enterprise DTC brands who want a dedicated Klaviyo partner with a strong track record.

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2. Underground Ecom

⭐ Featured Partner

Underground Ecom has built a reputation in the performance eCommerce space, with strong email and SMS capabilities anchored in Klaviyo. They lean heavily on data-driven optimization and are known for working with high-growth DTC brands where revenue attribution and testing cadence are priorities.

Best for: Growth-stage brands that want aggressive optimization and A/B testing baked into the retainer.

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3. Magnet Monster

Magnet Monster is a UK-based Klaviyo agency with a sharp focus on retention marketing for eCommerce. They've built a distinct voice in the industry — their thought leadership is substantive, and their approach to email marketing strategy goes beyond template execution. Notably strong on copywriting and creative, which matters more than most brands realize.

Best for: Brands that care about email as a brand-building channel, not just a revenue lever.

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4. Chronos Agency

Chronos Agency is an Asia-Pacific-based Klaviyo partner that has scaled significantly across global DTC brands. They bring a methodical, process-driven approach to retention marketing and are particularly strong on lifecycle email strategy. Good option if you're looking for strong execution at a competitive price point relative to US-based agencies.

Best for: Scaling brands looking for a high-quality but cost-efficient Klaviyo agency with global experience.

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5. Tinuiti

Tinuiti is one of the largest independent performance marketing agencies in the US, with a dedicated email and CRM practice. Their scale means they have deep bench strength and can integrate Klaviyo into a broader omnichannel strategy that includes paid search, social, and marketplace. The tradeoff is that you're not their smallest account — smaller brands may get less senior attention.

Best for: Established brands spending significantly on paid acquisition who want email tightly integrated with their full marketing stack.

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6. SmartBug Media

SmartBug is a full-service digital agency with strong HubSpot roots that has expanded into eCommerce and Klaviyo. They bring a sophisticated understanding of marketing automation and customer journey design. Particularly good if your brand has a complex pre-purchase consideration cycle that requires nurture sequences beyond standard eCommerce flows.

Best for: Brands with longer purchase cycles or considered purchases who need sophisticated segmentation and nurture strategy.

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7. Retention Harbor

⭐ Featured Partner

Retention Harbor focuses specifically on retention and lifecycle marketing for eCommerce — Klaviyo is central to their offering. They're a smaller boutique, which means more direct access to senior strategists and tighter client relationships. Their positioning around retention metrics (LTV, repeat purchase rate, churn) signals the right priorities.

Best for: Brands that have customer acquisition dialed in and want to focus on maximizing LTV through email and SMS.

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8. Inbox Army

Inbox Army is an email-specialist agency with broad platform expertise including Klaviyo. They offer flexible service tiers — from full-service retainers to à la carte campaign execution — which makes them accessible to brands at different stages. Strong on execution and turnaround speed.

Best for: Brands that need reliable, high-volume campaign execution with flexibility in engagement model.

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How to Evaluate Any Agency Before You Hire

The list above is a starting point. Here's how to pressure-test any agency you're seriously considering:

Ask for a Klaviyo account audit. Any agency worth hiring should offer a discovery call that includes a review of your current account. If they're not asking to see your flows, open rates, and list health before proposing — that's a flag.

Request references from similar brands. Don't just ask for case studies. Ask to speak with a current client in a similar category or revenue stage. Thirty minutes on the phone with a real client will tell you more than any proposal doc.

Understand their reporting cadence. How often will you get reports? What metrics matter to them — open rate (a vanity metric since iOS privacy changes), click rate, revenue attributed, list growth? Agencies focused on the right metrics signal strategic maturity.

Clarify ownership and portability. You should own your Klaviyo account, your templates, and your flows — always. Make sure any contract is explicit about this. Switching agencies should never mean starting from scratch.

Start with a scoped project. Many brands go straight to a 12-month retainer. Consider starting with a 60–90 day engagement focused on a specific deliverable — a flow audit and rebuild, or a campaign strategy sprint. This gives both sides a low-stakes way to evaluate fit before the long-term commitment.

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Find Your Agency

The agencies listed here are some of the strongest in the Klaviyo ecosystem — but they're not the only ones. Depending on your niche, budget, or geography, the right fit might be a boutique specialist you haven't heard of yet.

That's exactly why we built KlaviyoDirectory.com/directory — a curated, searchable directory of vetted Klaviyo agencies and freelancers, organized by specialty, pricing model, and the types of brands they serve best.

Whether you're a seven-figure DTC brand looking for a strategic Klaviyo partner or a scaling startup that needs someone to build your foundations right the first time, the directory gives you a shortlist of Klaviyo experts worth talking to.

Browse the full directory →

Stop guessing. Find the right Klaviyo agency for your brand, faster.