This research explored how and why knowledge sharing matters for R&D engineers by investigating the effects of knowledge sharing on R&D engineer's job performance and job satisfaction. Based on multilevel data of 242 R&D engineers from 55 teams, the results showed that the relationships between knowledge sharing and R&D engineer's job performance/satisfaction were mediated through individual learning and self‐efficacy. Individual learning was a necessary step for knowledge sharing to transform into individual knowledge, which in turn enhanced individual level outcomes. At the same time, individual learning enhanced self‐efficacy, which subsequently benefited R&D engineer's job performance and job satisfaction. Finally, individual learning was found to be strongly related to individual job satisfaction.