We investigate the associations among physical appearance, threat perceptions, and criminal punishment. Psychological ideas about impression formation are integrated with criminological perspectives on sentencing to generate and test unique hypotheses about the associations among defendant facial characteristics, subjective evaluations of threatening appearance, and judicial imprisonment decisions. We analyze newly collected data that link booking photos, criminal histories, and sentencing information for more than 1,100 convicted felony defendants. Our findings indicate that Black defendants are perceived to be more threatening in appearance. Other facial characteristics, such as physical attractiveness, baby‐faced appearance, facial scars, and visible tattoos, also influence perceptions of threat, as do criminal history scores. Furthermore, some physical appearance characteristics are significantly related to imprisonment decisions, even after controlling for other relevant case characteristics. These and other findings are discussed as they relate to psychological research on impression formation, criminological theories of court actor decision‐making, and sociological work on race and punishment.