Online learning has recently replaced traditional offline learning as the mainstream learning model for Chinese college students owing to the COVID-19 pandemic. This study examined the relationship between online self-regulated learning and academic procrastination among 1149 Chinese undergraduates who participated in online learning. The effects of online self-regulated learning on academic procrastination and whether it was mediated by attention control and moderated by peer support were investigated. Mediation analyses revealed that attention control partially mediates online self-regulated learning and academic procrastination. Peer support moderated the direct effect of online self-regulated learning and the mediating effect of attention control on academic procrastination. Our findings provide important ways to reduce academic procrastination and mitigate the adverse impacts of online learning.