In this letter, we present a multi-channel in-plane-gate field effect transistor (MC-IPGFET). In the proposed device, multiple vertically stacked two-dimensional electron gases (2DEGs) are simultaneously controlled by lateral in-plane gates formed with the same multi-2DEG stack. The multi-channel heterostructure allows to increase carrier density in the channel while keeping high electron mobility. Besides, the in-plane gate geometry provides an effective control of multiple channels with a smaller intrinsic gate capacitance. As compared to single-channel IPGFETs, multi-channel structure resulted in a three-time enhancement in current density and transconductance, offering opportunities for efficient scaling up of in-plane gate devices. High current density of 4.35 A/mm along with 2.05 S/mm transconductance are achieved in an optimized device. The effective control of the multiple high-mobility channels along with the reduced intrinsic capacitance of the in-plane gate open a pathway for new device concepts.