Large-scale energy storage technologies are in high demand for effective utilization of intermittent electricity generations and efficient electric power transmission. The feasibility of lithium-ion batteries for large-scale energy storage is under debate due to the scarcity and uneven distribution of lithium resources in the Earth's crust. Therefore, there arises tremendous interest in pursuing alternative energy storage systems based on earth-abundant materials. Recently, non-aqueous potassium-ion batteries (KIBs) are emerging as a promising energy storage system due to the abundance of potassium and the encouraging battery performance. Here, the recent research progress in non-aqueous KIBs is summarized, including electrode materials, electrolytes, battery architectures and fundamental electrochemical processes. The challenges and future research opportunities are also briefly discussed.