Glycolysis of poly(ethylene terephthalate) (PET) is one of the main methods by which PET is recycled, which is in the need of an inexpensive and efficient catalyst. We report a glycolysis reaction of PET into bis(hydroxyethyl) terephthalate (BHET) catalyzed by ultrathin exfoliated MnO2 nanosheets (e-MON). The exfoliation of MnO2 was achieved using a shear flow system with a mixing behavior that facilitates the intercalation of potassium ions into the interlayer voids of MnO2, delaminating MnO2 into the mono- and few-layer e-MON. Glycolysis was optimized by varying the reaction temperature, time, and loading of e-MON. The e-MON catalyst provided a BHET yield of 100 % for a reaction lasting 30 min at 200 °C, which was much higher than the 77.6 % yield achieved with bare bulk MnO2. The high yield persisted over five cycles, demonstrating the reusability of the e-MON catalyst.