Disclosed are various approaches for authenticating a user through a voice assistant device and creating an association between the device and a user account. The request is associated with a network or federated service. The user can use a client device, such as a smartphone, to initiate an authentication flow. A passphrase is provided to the client device can captured by the client device and a voice assistant device. Audio captured by the client device and voice assistant device can be sent to an assistant connection service. The passphrase and an audio signature calculated from the audio can be validated. An association between the user account and the voice assistant device can then be created.