Bulk-Unsubscribe Email & SMS from a Klaviyo Flow (Webhook)

Walkthrough video

Step-by-step screen recording: https://fathom.video/share/bX6jBA-TwonmHxgoxFsZP2RhntcGC3Qy

Why the default sunset template falls short

Klaviyo’s “Sunset Unengaged Subscribers”–style templates often end with a profile action such as setting a custom property (for example “Unengaged” = true). That tags the person but does not revoke marketing consent. For deliverability and compliance, you usually want a true unsubscribe from email and SMS marketing — which you can do with a flow Webhook that calls Klaviyo’s Bulk Unsubscribe Profiles API.

API reference and an important caveat

Official endpoint documentation: https://developers.klaviyo.com/en/reference/bulk_unsubscribe_profiles. Klaviyo warns that profiles not in a specified list may be globally unsubscribed when using this job — design your flow and audience so only the right people hit this Webhook, and read the latest docs before going live.

In Klaviyo, go to Account → Settings → API keys and create a new private key used only for this flow Webhook. Grant the scopes required for the Bulk Unsubscribe endpoint (see the API reference — typically lists, profiles, and subscriptions write access). Copy and store the key in a password manager: Klaviyo will not show the full secret again later. You will paste it into the Webhook’s Authorization header as Klaviyo-API-Key YOUR_KEY.

Open your sunset or bot flow in the flow editor. Remove or bypass the profile-property step that only marks someone as unengaged (or equivalent). Add an action: Webhook (HTTP request). Set the method to POST. You will point it at Klaviyo’s bulk unsubscribe jobs URL in the next step.

Use POST to https://a.klaviyo.com/api/profile-subscription-bulk-delete-jobs — this is the Bulk Unsubscribe Profiles job endpoint described in Klaviyo’s reference. Do not use a browser GET; the flow must send JSON in the body.

In the Webhook configuration, add one header row per line below. Replace INSERT-API-KEY with the private key you saved (after Klaviyo-API-Key and a space). You may use a newer revision date if Klaviyo’s docs specify one for this endpoint.

accept: application/json
content-type: application/json
revision: 2025-07-15
Authorization: Klaviyo-API-Key INSERT-API-KEY

Use the payload below. {{person.email}} and {{person.phone_number}} are Klaviyo profile variables so each recipient is unsubscribed individually. Phone should be in E.164 if present. If someone has no phone, behavior depends on Klaviyo’s validation — you may need a branch or trimmed payload for SMS-disabled profiles (see the last step).

{
  "data": {
    "type": "profile-subscription-bulk-delete-job",
    "attributes": {
      "profiles": {
        "data": [
          {
            "type": "profile",
            "attributes": {
              "email": "{{person.email}}",
              "phone_number": "{{person.phone_number}}",
              "subscriptions": {
                "email": {
                  "marketing": {
                    "consent": "UNSUBSCRIBED"
                  }
                },
                "sms": {
                  "marketing": {
                    "consent": "UNSUBSCRIBED"
                  },
                  "transactional": {
                    "consent": "UNSUBSCRIBED"
                  }
                }
              }
            }
          }
        ]
      }
    }
  }
}

Use Klaviyo’s Webhook Preview with a real test profile. Preview actually executes the Webhook against that example profile — it is not a dry run. Confirm the profile’s email/SMS marketing consent updates as expected. If something fails, inspect request and error details in the developer dashboard: https://www.klaviyo.com/developer-tools/dashboard

When SMS is not set up for the account, including SMS blocks in the JSON can produce a 400 response. Remove the entire sms object under subscriptions (and omit phone_number if unused) so the job only unsubscribes email marketing. Re-test with Preview. Keep the API key scoped and rotate it if it is ever exposed.