The significant proliferation of renewable resources, primarily inverter interfaced distributed generation (IIDG) in the utility grid, leads to a dearth of overall inertia. Subsequently, the system illustrates more frequency nadir and a steeper frequency response. This may degrade the dynamic frequency stability of the overall system. Further, virtual inertia has been synthetically developed in IIDG, which is known as a virtual synchronous generator (VSG). In this work, a novel STO-STC-based controller has been developed, which offers flexible inertia following system disturbance. The controller is based on the super-twisting algorithm (STA), which is a further advancement in the conventional sliding mode control (SMC), and has been incorporated in the control loop of the VSG. In this scheme, two steps have been implemented, where the first one is to categorize all states of the system using a super-twisting observer (STO) and further, it is required to converge essential states very quickly, exploiting a super-twisting controller (STC). Thus, the STO-STC controller reveals a finite-time convergence to the numerous frequency disturbances, based on various case studies. The performance of the controller has been examined in the MATLAB environment with time–domain results that corroborate the satisfactory performance of the STO-STC scheme and that illustrate eminence over the state of the art.