A spokesmodel is a person that is hired to represent your organization in advertising or marketing campaigns. They can be celebrities, musicians, athletes, or models. In order succeed at this type of modeling, one must be attractive, confident, and articulate.
Spokesmodels serve two purposes;
Attract attention
Speak for you and engage patrons
Experienced spokes models serve you and speak on your behalf in media campaigns or person at promotional events. They learn about your products or services and can articulate their benefits and value proposition to consumers. This type of staff is equally comfortable behind the camera as in person.

On utilise aussi "égérie", mais plus dans le domaine du luxe, de la haute couture.
https://brandandcelebrities.com/a-propos-celebrity-marketing...

Autre traduction possible de « spokesmodel ». Impossible de faire un choix sans plus de contexte.