The integration of optical interconnects with silicon-based electronics can address the growing limitations facing chip-scale data transport as microprocessors become progressively faster. However, until now, material lattice mismatch and incompatible growth temperatures have fundamentally limited monolithic integration of lasers onto silicon substrates. Here, we use a novel growth scheme to overcome this roadblock and directly grow on-chip InGaAs nanopillar lasers, demonstrating the potency of bottom-up nano-optoelectronic integration. Unique helically propagating cavity modes are used to strongly confine light within subwavelength nanopillars despite the low refractive index contrast between InGaAs and silicon. These modes therefore provide an avenue for engineering on-chip nanophotonic devices such as lasers. Nanopillar lasers are as-grown on silicon, offer tiny footprints and scalability, and are thus particularly suited to high-density optoelectronics. They may ultimately form the basis of future monolithic light sources needed to bridge the existing gap between photonic and electronic circuits. © 2011 Macmillan Publishers Limited. All rights reserved.