Building on theories of impression formation based on faces, this research investigates the impact of job candidates’ facial age appearance on hiring as well as the underlying mechanism. In an experiment, participants decided whether to hire a fictitious candidate aged 50 years, 30 years or without age information. The candidate's age was signalled either via chronological information (varied by date of birth) or via facial age appearance (varied by a photograph on the résumé). Findings showed that candidates with older‐appearing faces – but not chronologically older candidates – triggered impressions of low health and fitness, compared to younger‐appearing candidates. These impressions reduced perceptions of person–job fit, which lowered hiring probabilities for older‐appearing candidates. These findings provide the first evidence that trait impressions from faces are a determinant of age discrimination in personnel selection. They call for an extension of current models of age discrimination by integrating the effects of face‐based trait impressions, particularly with respect to health and fitness.