A balloon illumination and inflation device has a tubular housing assembly comprising a balloon neck attachment at one end, an inflation mouthpiece at an opposite end; an air valve adjacent the mouthpiece, a lamp mount adjacent the one end to direct light into the attached balloon; an internal battery mount and a switch to connect the lamp to the battery circuit for illumination of the balloon interior. The switch is formed by first and second tubular housing members relative rotatable to close the air valve means and simultaneously to connect the battery circuit to the lamp.