The first examples of bifunctional hyperbranched polymers (HBP) with high density ionic liquid (IL) moieties in the main chain and controllable amount of pyrene groups at the chain ends (Py-HBPIL) have been synthesized via a facile three-step procedure, which were then immobilized onto reduced graphene oxide (rGO) via π–π stacking interactions. Py-HBPIL(Br) bearing pyrene groups at 10% of the chain ends allowed the highest immobilization loading of 73% in weight. The resultant Py-HBPIL(Br)@rGO hybrid material displayed much better catalytic activity than ever reported for immobilized IL catalysts for coupling reaction between CO₂ and propylene oxide (PO), and it could be reused up to 6 times by simple filtration process without significant decline in activity. Furthermore, the combination of bifunctional HBP and π–π stacking immobilization may provide a general and versatile platform to design highly active, selective and recyclable catalysts for various chemical transformations.