An apparatus for heating hot beverage containers includes a housing having an upper end, a lower end, and a sidewall extending between the upper and lower ends of the housing. The upper end of the sidewall has oppositely disposed, downwardly curving portions that define oppositely disposed openings at the upper end of said housing. The apparatus includes a heater assembly located at the lower end of the housing. The apparatus has a controller including an electrical circuit in communication with the heater assembly, and a switch located on the sidewall of the housing for activating the heater assembly. A hot beverage container with an insulating sleeve is inserted into the housing. A sidewall of the container engages the switch and a bottom wall of the container is in thermal communication with the heater assembly. The heater assembly heats liquid in the container through the bottom wall of the container.