We present the monolithic integration and electrical characterization of InAs nanowires (NWs) with the well-defined geometries and positions on Si as a platform for quantum transport studies. Hereby, one-dimensional (1D) ballistic transport with step-like 1D conductance quantization in units of 2e2/h is demonstrated for NWs with the widths between 28 nm and 58 nm and a height of 40 nm. The electric field control of up to four individual modes is achieved. Furthermore, the sub-band structure of the nanowires is investigated using bias spectroscopy. The splitting between the first and the second sub-band increases as the width of the NWs is reduced, whereas the degeneracy of the second sub-band can be tuned by the symmetry of the NW cross section, in accordance with a “particle in a box” model. The length-dependent studies reveal ballistic transport for up to 300 nm and quasi-ballistic transport with a mean free path of 470 nm for longer InAs NW channels at 30 K. We anticipate that the ballistic 1D transport in monolithically integrated InAs NWs presented here will form the basis for sophisticated quantum wire devices for the future integrated circuits with additional functionalities.