This study examined the relationship between academic procrastination and psychological well-being among vocational college students in Guizhou, China. Testing the mediating role of school belonging and the moderating role of gender. A cross-sectional survey was conducted with 377 full-time students from three vocational colleges in Zunyi, Guizhou Province, using stratified random sampling by institution and grade. Previously validated five-point Likert scales were used, and hypotheses were tested using structural equation modelling with bias-corrected bootstrapping (5,000 resamples). Academic procrastination negatively predicted psychological well-being (β = −0.359, p < .001) and school belonging (β = −0.376, p < .001), while school belonging positively predicted psychological well-being (β = 0.252, p < .001). School belonging partially mediated the procrastination–well-being association (indirect effect β = −0.095, 95% BC CI [−0.146, −0.053], p < .001). Gender did not moderate the procrastination-to-belonging pathway (β = 0.009, p = .845). The model explained 14.2% of the variance in school belonging and 26.0% in psychological well-being. Overall, the findings indicate a partially mediated mechanism whereby academic procrastination is associated with poorer psychological well-being both directly and indirectly through reduced school belonging, whereas the hypothesised gender moderation was not supported. These results position school belonging as a salient contextual mechanism linking academic procrastination to vocational students’ psychological well-being in this Chinese sample. Findings suggest that enhancing school belonging, alongside reducing procrastination, may improve vocational students’ psychological well-being.