Each pet litter tray of the nested disposable pet litter trays includes a rear portion and a front portion. The front portion includes a pair of front sidewalls, with each of the front walls having a plurality of slits formed therethrough. Following a pet's deposit of excretory waste in pet litter contained in the topmost tray, the user may grip front gripping edges of the front sidewalls and squeeze them together to form a funnel- or spout-shaped dry pet litter dispenser, the user angling the tray so that the pet litter and the excretory waste enter the dry pet litter dispenser, with dry, reusable pet litter falling through the plurality of slits into the next lower tray in the nested stack for reuse, with wet pet litter and the excretory waste being trapped within the front portion for transport and disposal.