III-V materials, such as InGaAs and InP, are highly attractive for high-performance electronics and optoelectronics owning to their high carrier mobilities and potential for bandgap engineering. Integration on silicon substrates, however, is a key requirement to enable widespread adoption of these materials. In this work, direct wafer bonding (DWB) of III-V materials is explored as a low-temperature enabling technology for Si integration. For high-performance logic and RF electronics, DWB is compared to competing integration technologies and is shown to exhibit higher device performance due to its relatively low process complexity and thermal impact (300 °C). Due to the low thermal impact of DWB, it is also uniquely suitable for 3-D integration, i.e., vertical stacking of multiple functional layers. III-V optoelectronics are attractive in such 3-D stacks, where they can enable high-efficiency tunable lasers together with Si photonics integrated circuits. DWB is here compared to selective epitaxy as an integration route for InP-on-Si microdisk lasers. Plasmonics are explored as well, allowing scaling of integrated III-V photonic devices beyond the diffraction limit of light. The results of this work show that DWB is a highly promising integration route for III-V materials for both electronics and optoelectronics applications.