What This Integration Does
This integration uses Twilio as the SMS delivery layer behind Klaviyo’s segmentation and flow engine, giving the business Klaviyo’s behavioural targeting with Twilio’s deliverability, throughput, and international reach. SMS sends from Klaviyo flows route through Twilio numbers. Twilio status callbacks update Klaviyo with delivery, failure, and reply events. Inbound replies trigger Klaviyo metrics that can drive subsequent flows.
For merchants who outgrew Klaviyo’s native SMS, the reasons are usually international reach, sender ID flexibility, or carrier deliverability. This integration keeps the Klaviyo brain and swaps in Twilio’s muscle.
The Workflow
When a Klaviyo flow triggers an SMS send, the integration receives the outbound payload, picks the correct Twilio number or short code based on the recipient country and brand, sends the message through Twilio, and immediately reports back the message SID and initial status to Klaviyo as a custom metric.
A specific chain: a Klaviyo abandoned-cart flow fires for a UK customer. The integration sends the SMS through a UK alphanumeric sender ID via Twilio, and within seconds Twilio reports “delivered.” Klaviyo records the delivery and the flow continues. Forty minutes later, the customer replies with a question. Twilio receives the inbound, the integration writes the reply text and timestamp to Klaviyo as a “Replied to SMS” metric on the profile, and triggers a flow that routes the message to the customer service inbox and pauses any further outbound SMS to that customer for forty-eight hours.
International routing is where this integration earns its place. A US customer on the same flow gets a long code through a US Twilio number. A French customer gets a sender ID compliant with French regulations. The same Klaviyo flow targets all three because the integration handles the country-specific routing transparently.
Before and After
Before, the merchant either uses Klaviyo’s native SMS, which is fine for US-centric stores but limited internationally, or runs SMS entirely outside Klaviyo and loses the behavioural segmentation that made Klaviyo worth choosing. Reporting on SMS performance is partial because the data lives in two places.
After, Klaviyo’s segmentation drives the message, Twilio delivers it, and every status flows back to Klaviyo so reporting and follow-up flows work end to end. International sends respect local regulations automatically.
Who Needs This
International e-commerce brands using Klaviyo for email and looking for serious SMS reach. Beauty, fashion, supplements, and lifestyle brands shipping across the UK, EU, and North America are the typical fit. The trigger is usually a deliverability problem with the native SMS provider or a regulatory issue with sender ID in a specific market.
How We Build This
We build this against the Twilio Programmable Messaging API and the Klaviyo Track and Events APIs. The routing logic (which Twilio number for which country, which sender ID for which brand) is configured per merchant. Status callbacks are signed and queued. See Twilio API Integration and Klaviyo API Integration for the underlying capabilities.
Get Twilio and Klaviyo Connected
If Klaviyo is your segmentation engine and you need SMS delivery that works internationally, we can build a custom integration that uses Twilio behind the scenes without losing the Klaviyo flow logic. We also connect WhatsApp to Klaviyo for conversational messaging and Twilio to Mailchimp for SMS-driven email lists. The integrations overview covers the full range of communication integrations we build.
Written by
Alex
CEO
I’m a software developer and CEO of Digital Royalty, helping growing teams scale their SaaS platforms without losing quality, visibility, or control. I focus on building structured, maintainable systems with clear processes, reporting, and accountability. With over a decade of experience across agency and in-house roles, I specialise in delivering long-term, scalable solutions that support complex, evolving products.
