Are you looking for an agency to manage email and SMS marketing for your ecommerce store through Klaviyo?

We created this list of the top five Klaviyo agencies that can help you with this.

1. Flowium

About: Flowium is a full-service email marketing agency founded in the early 2010s that specializes in Klaviyo email and SMS marketing for ecommerce brands. As a Klaviyo Master Elite Partner, Flowium delivers data-driven email marketing strategies focused on maximizing engagement and repeat purchases for growth-stage DTC brands.

Website: Flowium.com

Flowium stands out for its hands-on, turnkey execution model. Rather than simply designing flows, the team actively manages your entire Klaviyo program including campaign strategy, audience segmentation, and conversion tracking. This makes them especially valuable for teams that need consistent, conversion-focused email and SMS marketing but lack in-house capacity to execute at a high level.

2. Chronos Agency

About: Chronos Agency is a lifecycle marketing agency founded in 2017 that helps high-growth DTC brands scale profits through email, SMS, and push marketing. With a global team of 80+ members and offices in Singapore, Australia, and the United States, Chronos specializes in retention-first marketing strategies that drive 20-30% revenue increases.

Website: Chronos.Agency

Chronos Agency differentiates itself through its emphasis on post-purchase lifecycle strategy and customer retention. Where many agencies focus primarily on acquisition, Chronos builds comprehensive retention systems using behavior-based flows that maximize customer lifetime value. Their data-driven approach and cross-industry experience make them particularly effective for brands seeking sustainable, long-term growth through owned channels.

3. InboxArmy

About: InboxArmy is a full-service email marketing agency founded in 2016 that serves mid-sized businesses to enterprise clients across 25+ industries. As a Klaviyo Silver Master Partner, they provide comprehensive email marketing solutions from strategy and automation to template production and deliverability optimization.

Website: InboxArmy.com

InboxArmy’s strength lies in their cross-platform expertise and ability to handle high-volume email operations at scale. With a team of 120+ certified email marketers, they excel at managing complex, multi-send programs without sacrificing performance or personalization. Their platform-agnostic approach and deep technical knowledge make them ideal for enterprise brands with aggressive send schedules and sophisticated segmentation needs.

4. Underground Ecom

About: Underground Ecom is a retention marketing agency that specializes exclusively in ecommerce email and SMS marketing through Klaviyo. Named Klaviyo Partner of the Year 2025 and holding the highest Klaviyo Master Elite status, Underground Ecom works with 8, 9, and 10-figure ecommerce brands across the US and UK.

Website: UndergroundEcom.com

Underground Ecom sets itself apart through its narrow specialization in retention and customer lifetime value optimization. Their team of 100+ members functions as an integrated CRM arm of your business, providing end-to-end Klaviyo account management including strategy, content creation, A/B testing, technical support, and reporting. This deep integration approach delivers an in-house experience with the expertise of a specialized agency.

5. StubGroup

About: StubGroup is a digital marketing agency founded in 2012 that offers services including Google Ads management, SEO, email marketing, and Klaviyo setup and management. They specialize in helping ecommerce brands optimize their email marketing programs and have expertise in platform migrations, including moving from Yotpo to Klaviyo.

Website: StubGroup.com

What distinguishes StubGroup is their comprehensive approach to email marketing transformation. Their case studies demonstrate impressive results: one perfume brand saw a 390% month-over-month revenue increase from email with 87% coming from automations, while another client achieved a 58% revenue growth in just 30 days. StubGroup focuses on foundational automations including Browse Abandonment, Welcome Series, Post-Purchase flows, and strategic campaign planning combined with robust segmentation strategies for maximum ROI.

Choosing a Klaviyo Agency for Your Ecommerce Store: Key Considerations

When selecting a Klaviyo agency to manage your email and SMS marketing, you’ll want to evaluate several critical factors to ensure you’re partnering with the right team for your business.

Experience with Ecommerce and Your Platform

Look for agencies that specialize in ecommerce marketing, particularly those with proven experience managing campaigns for stores on your platform (Shopify, WooCommerce, BigCommerce, etc.). They should understand the unique challenges of online retail, including product lifecycle management, seasonal fluctuations, and conversion optimization specific to ecommerce.

Proven Track Record and Results

Request case studies and references from similar businesses. A reputable agency should be able to demonstrate:

• Measurable revenue increases from email and SMS
• Success stories with stores in your industry or niche
• Clear metrics like email-attributed revenue, open rates, click rates, and conversion rates
• Before-and-after campaign performance data showing actual growth

Comprehensive Service Offering

The ideal agency should provide:

• Email automation expertise (welcome series, cart abandonment, browse abandonment, post-purchase)
• SMS marketing integration and strategy
• Campaign planning and calendar management
• List segmentation and audience targeting
• Template design and mobile optimization
• Regular reporting and transparent communication
• A/B testing and optimization

Strategic Approach

Evaluate whether the agency takes a strategic, consultative approach rather than just tactical execution. They should ask detailed questions about your business goals, customer lifecycle, average order value, purchase frequency, and competitive landscape before proposing solutions. The best agencies focus on retention and customer lifetime value, not just one-off campaigns.

Pricing Structure and Transparency

Understand their fee structure, whether it’s a flat monthly retainer, percentage of email revenue, or custom pricing based on scope. Most agencies charge between $1,500 and $10,000+ per month depending on services and complexity. Ensure there are no hidden costs and that deliverables are clearly defined.

Communication and Reporting

Choose an agency that provides regular, clear reporting with actionable insights. You should have a dedicated account manager and established communication channels. Ask how often you’ll receive updates, what metrics will be included in reports, and how they measure success.

Technical Capabilities

The agency should be proficient in:

• Klaviyo platform mastery including advanced flows and conditional logic
• Integration with your ecommerce platform
• Segmentation strategies based on customer behavior
• Deliverability optimization and list hygiene
• Migration from other email platforms if needed

Cultural Fit and Accessibility

Consider whether the agency’s communication style, values, and availability align with your needs. Will you have direct access to the strategists managing your campaigns, or will you only interact with account coordinators? The best partnerships feel collaborative rather than transactional.