Time theft is a prevalent, costly, and generally discreet employee activity in firms; nonetheless, very limited research is available on it. To explore why, how, and when employees exhibit time theft, we investigate the influence mechanism of work-related use of information and communication technologies after hours (W_ICTs) on time theft from the perspective of resource gain and loss. Our study found that W_ICTs significantly promotes employee time theft. Emotional exhaustion and moral disengagement play a mediating role in the relationship between W_ICTs and time theft, respectively, and these two variables have a chain-mediating role in the relationship above. Perceived organizational support moderates this chain mediation by moderating the positive effect of W_ICTs on emotional exhaustion. Overall, the findings have important theoretical and managerial implications for research on W_ICTs and time theft.