A method for facial authentication of a wearer of a watch includes: initiating an authentication process including detecting at least one triggering movement/gesture carried out by the wearer; capturing at least one sequence of images relative to the face of the wearer pivoting from one direction to another in front of the optical sensor; acquiring surface geometric data of the face associated with each image of at least one sequence; generating a three-dimensional model of the face of the wearer from at least one captured sequence of images and from the acquired geometric data; determining an identification index generated based on identification data relative to a plurality of features characteristic of the face of the wearer of the watch detected on the basis of the three-dimensional model, and identifying the wearer if the identification index is greater than a reference identification index.