Punishments are not always administered immediately after a crime is committed. Although scholars and researchers claim that third parties should normatively enact punishments proportionate to a given crime, we contend that third parties punish transgressors more severely when there is a time delay between a transgressor’s crime and when they face punishment for it. We theorize that this occurs because of a perception of unfairness, whereby third parties view the process that led to time delays as unfair. We tested our theory across eight studies, including two archival data sets of 160,772 punishment decisions and six experiments (five preregistered) across 6,029 adult participants. Our results suggest that as time delays lengthen, third parties punish transgressors more severely because of increased perceived unfairness. Importantly, perceived unfairness explained this relationship beyond other alternative mechanisms. We explore potential boundary conditions for this relationship and discuss the implications of our findings.