Direct integration of high-mobility Ⅲ–Ⅴ compound semiconductors with existing Si-based complementary metal-oxide-semiconductor (CMOS) processing platforms presents the main challenge to increasing the CMOS performance and the scaling trend. Silicon hetero-nanowires with integrated Ⅲ–Ⅴ segments are one of the most promising candidates for advanced nano-optoelectronics, as first demonstrated using molecular beam epitaxy techniques. Here we demonstrate a novel route for InAs/Si hybrid nanowire fabrication via millisecond range liquid-phase epitaxy regrowth using sequential ion beam implantation and flash-lamp annealing. We show that such highly mismatched systems can be monolithically integrated within a single nanowire. Optical and microstructural investigations confirm the high quality hetero-nanowire fabrication coupled with the formation of atomically sharp interfaces between Si and InAs segments. Such hybrid systems open new routes for future high-speed and multifunctional nanoelectronic devices on a single chip.