State-of-the-art CubeSat electric power system (EPS) architectures employ multiple dc-dc converters to regulate the load voltage and maximize the solar energy harvest. However, this leads to the use of multiple bulky inductors in the CubeSat EPS which is much constrained by strict volume and weight restrictions. With the aim of achieving smaller EPS footprint, this paper presents a new single-inductor based multiple-input multiple-output (MIMO) converter for CubeSat EPS. The operational principles of the proposed converter and its steady-state analysis are discussed, and converter modeling is performed. A control strategy is developed to achieve voltage regulation of the CubeSat loads and maximum power point tracking (MPPT) for the PV panels under a wide-range of irradiation conditions. An experimental prototype based on the 1U CubeSat specifications is developed to validate the performance of the proposed MIMO converter.