Add variant sizes in the export to Klaviyo

Technical Q&A

Topic summary

A user wants to include product variant sizes (e.g., clothing sizes) in fulfilled order data being sent from Shopify to their email platform, Klaviyo.

Proposed Solution:

  • Customize the event payload if variant size data is missing in Klaviyo
  • Use either Klaviyo’s custom webhooks or Shopify’s API to transmit the additional data

Implementation Approach:
A code example was provided showing how to structure the API call with:

  • Klaviyo public API key
  • Custom event name (“Fulfilled Order with Variant”)
  • Customer email
  • Product details including the variant size field

Status: The question remains open with one technical response provided but no confirmation of implementation or further discussion.

Summarized with AI on October 29. AI used: claude-sonnet-4-5-20250929.
1

i want to add the variant sizes to the fullfilled order and send that information to our email platform Klaviyo. How can i add these information in the event that’s being send from Shopify to Klaviyo

2

Hi,

Hope this will help

  • Customize Event If Variant Size Is Missing in klaviyo
  • Use Klaviyo’s Custom Webhooks or Shopify’s API

Code example (API)

{
  "token": "YOUR_KLAVIYO_PUBLIC_API_KEY",
  "event": "Fulfilled Order with Variant",
  "customer_properties": {
    "$email": "customer@example.com"
  },
  "properties": {
    "Product": "T-Shirt",
    "Variant Size": "Large"
  }
}