A collapsible disposable cat litter box comprises a collapsible closure means by which the used litter box can be sealed closed quickly for easy disposal. The box comprises a moisture-proof enclosure with collapsible closure means extending from the side walls of the enclosure. The collapsible closure means includes two rigid top panels and two foldable panels. The foldable panels are scored so that they may be pushed inward to close the top of the litter box quickly. The side panels also include a horizontal score line so that the upper portion of the side panels may be folded down to enhance the rigidity of the litter box.