In this paper, a DC-DC converter designed specifically for the case of an input voltage with flicker to generate a DC output without oscillations. The PI controller of the DC-DC converter is designed to be variable gain and adaptive to the input voltage signal. The designed system has been first tested in the Matlab/Simulink environment with the rectified form of the synthetic input voltage signals generated based on the test signals with flicker recommended in the IEC 61000-4-15 Flickermeter Standard and the output voltage is controlled. The output voltage obtained by the proposed system and the standard PI controlled system are compared for various input signals with flicker and it has been observed that significant reduction in the output oscillation is obtained. The proposed system also reduces the initial overshoot of the output voltage. The proposed input voltage adapted VGPI controller has also been tested by the rectified form of the actual power system voltage signals obtained from the transformer substations supplying electric arc furnaces causing serious levels of voltage flicker. It has been shown that the oscillations at the output voltage of the proposed DC-DC converter is significantly reduced.