The implementation of innovative ideas has been argued to be important for the survival and growth of organizations. However, the conditions that promote the implementation of innovative ideas particularly at an individual level have been relatively less examined. Building on prior research on person–supervisor fit and idea implementation, we have theorized and tested the conditions under which proactive personality congruence between a supervisor and a follower increases the implementation of innovative ideas at the workplace. Based on polynomial regression of time-lagged, multisource data collected from 346 dyads, our study supported the hypothesis that congruence in proactive personality between a supervisor and a follower promotes idea implementation. In addition, our results indicated that the effect of congruence on idea implementation is strongest when the congruence in proactive personality is at higher rather than at the lower levels. Our study further revealed the effect of asymmetrical incongruence in follower– supervisor proactive personalities on idea implementation. The findings of our study have significant implications for research and practice.