A method is provided for self-provisioning and personalization of a companion device. A primary user device receives input to initiate a cellular service activation process for a companion device, wherein the companion device includes a preloaded version of a service provider application for facilitating remote provisioning. The primary device provides, to the companion device, an updated version of the service provider application that replaces the preloaded version. The primary device receives, from the companion device, an embedded universal integrated circuit card (eUICC) identifier for the companion device and forwards the eUICC identifier to a network device and an identifier for the primary device. When the network device verifies that the cellular service activation for the companion device can be provisioned, the primary device receives an activation code for the companion device to use to initiate a request for a new line of service for the eUICC identifier and forwards the activation code to the companion device.