The relationship between social capital and R&D team innovation has received increasing attention in the literature. However, little is known about the mechanisms between the two. This study aims to narrow the gap by investigating the mediating roles of psychological safety and learning from mistakes between the three dimensions of social capital and innovation at team level. Our sample comprised 151 R&D teams with 585 members from nine Chinese high-tech companies. The results showed that psychological safety and learning from mistakes (LFM) partially mediated the relationship between the structural and cognitive capital and innovation in R&D teams, and fully mediated the relationship between the relational capital and innovation in R&D teams. We further discussed subsequent managerial implications and future research directions.