AC/DC LED drivers often implement a boost converter to achieve bus voltage regulation by a conventional PI regulator cascaded with a notch filter. Notch filter is specifically designed for a certain frequency that necessitates the presence of a frequency measuring circuit like phase locked loop. This paper presents a disturbance observer-based filter to replace notch filter in such applications. The paper highlights adaptability of the proposed filter and shows comparative results to a standard notch filter. Simulation and preliminary hardware results confirm suitability of the proposed methodology for AC/DC boost converters for improving input current quality in lighting applications in terms of power factor and total harmonic distortion.