a deployable pet carrier assembly for a vehicle includes a sliding rail guide system configured to attach the pet carrier to a vehicle seat back and collapsible front , rear , and side walls defining a box structure when deployed . an actuator is provided , configured to retain or release the pet carrier walls for transitioning the pet carrier between a collapsed configuration and a deployed configuration . the sliding guide rail system includes front and rear guide rails configured to slidingly hold the pet carrier front wall and rear wall . a tray may be included to define a floor of the pet carrier .