A rolling extension tray bag dispenser rack includes a bag pack support tray that has a base, a first side wall, a second side wall, a back wall, a front wall and is sized and shaped to hold a merchandise bag pack. The front wall has an opening sized and shaped to permit extraction of bags from the pack. Rolling extenders are provided that have fixed portions and moving portions. The moving portions are attached to outer surfaces of the first and second side walls or the underside of the support tray and are slidably mounted to the fixed portions. The fixed portions have mounting features for attaching to an underside or back wall of a counter. A spring-loaded check ball or other latching mechanism is mounted to the support tray. A detent panel or other mating latching mechanism is mounted to the underside or back wall of the counter.