A concealed adjustable temperature switch is electrically connected to a heating member. The concealed adjustable temperature switch includes a fixed plate with a screw hole, an adjusting block having an outer threading threadedly engaged with the screw hole of the fixed plate, a bimetal plate that has different bending extents at different temperatures, and a metal plate. A positioning ring is securely mounted on the adjusting block to turn therewith. Two spaced stops are provided to stop a projection of the positioning ring, thereby limiting turning of the adjusting block.