Over the past three decades, scholarship on organizational citizenship behavior (OCB) has grown tremendously. Langer (1989) developed the Western approach of mindfulness, which included novelty seeking, novelty producing and engagement. The present study aimed to test the positive effect of mindfulness on OCB, and explore the mediating effect of the job craft. To test these hypotheses, Study 1 (N = 265) verified that mindfulness positively predicted OCB (whether self-report or peer-rating). Moreover, the effect of mindfulness on OCB was mediated by job crafting. Next, in a longitudinal design (Study 2), we recruited 93 university graduates to complete measures of mindfulness and control variables at Time 1. About One year later, at Time 2, participants completed measures of job craft and OCB. The results suggested that mindfulness had beneficial direct and indirect effects on OCB through the mediator of job craft, even when controlling for psychological capital and proactive personality. Finally, in a laboratory design (Study 3, N=90), compared to low mindfulness group and control group, participants with high level of mindfulness showed high level of OCB. Overall, these results suggest that individuals who have high level of mindfulness may show more organizational citizenship behavior, in part because mindfulness helps them make proactive changes in the work tasks and relationships (job crafting). Employees and organizations should focus on personal resources that can be developed and trained. And organizations could conduct training programs to develop employees’ mindfulness to improve OCB.