The interfacial nanoparticle compatibilization (INC) strategy has opened up a promising avenue toward simultaneous functionalization and interfacial engineering of immiscible polymer blends. While the INC mechanism has been well developed recently, few investigations have focused on rigid nanoplatelets because of the inherent steric hindrance of the surface-grafted polymer chains. Herein, surface-modified rigid nanoplatelets have been incorporated into an immiscible poly(l-lactide) (PLLA)/poly(butylene succinate) (PBSU) blend. It is demonstrated that the strong interfacial adhesion between PLLA and PBSU phases is promoted via molecular entanglements of the grafted chains on the surface of nanoplatelets with the individual components. A refined phase morphology with improved mechanical properties can be achieved with the addition of 5 wt % modified Gibbsite nanoplatelets. It was further found that the stiffness of nanoplatelets can change the geometry of the interface significantly. It is, therefore, indicated that the simultaneous interface strengthening and interfacial curvature controlling of rigid nanoplatelets originate from the selective swelling/collapse of the -formed PLLA and PBSU grafts within the corresponding phase at the interface. Such a mechanism is confirmed by the Monte Carlo simulations. This work provides new opportunities for the fabrication of advanced polymer blend nanocomposites.