Character strengths are hypothesized to contribute to human thriving. However, the effects of their use on individuals’ behaviors and attitudes at work, an important domain of modern life, have rarely been studied. In the present study, we examined associations of employees’ use of character strengths at work with productivity, organizational citizenship behavior (OCB), and job satisfaction. Based on the broaden-and-build theory of positive emotions, we suggested a multiple mediation model demonstrating how these associations are mediated by positive affect and engagement. Participants (N = 1,095) completed measures of strengths use, work productivity, OCB, job satisfaction, positive affect, and work engagement. As hypothesized, using strengths at work was associated with productivity, OCB, and job satisfaction, and these associations were mediated by higher positive emotions and engagement. The findings highlight the potential benefits of encouraging employees to use their strengths and point to positive affect and work engagement as mediating these effects.