We present a novel heterogeneous photonic integration of III/V on silicon by using epitaxial regrowth on III/V-on-Si wafer bonded substrates. This integration method decouples the correlated root causes, i.e., lattice, thermal, and domain mismatches, which are all responsible for a large number of detrimental dislocations in the heteroepitaxial process. The grown multi-quantum well vertical p–i–n diode laser structure shows a significantly low dislocation density of 9.5 × 104 cm−2, two orders of magnitude lower than the state-of-the-art conventional monolithic growth of III/V on Si. Hybrid InP-on-Si multi-quantum well lasers were successfully demonstrated with this heterogeneous integration and shown room-temperature pulsed and continuous-wave lasing. This generic concept can be applied to other material systems to provide higher integration density, more functionalities and lower total cost for photonics as well as microelectronics, MEMS, and many other applications.