In this study, a new flickermeter sensitive to high-frequency interharmonics and robust to fundamental frequency variations is proposed, implemented and tested. The standard IEC flickermeter, proposed in the 61000-4-15 IEC Standard, considers only the interharmonics around the fundamental frequency and ignores the effect of high-frequency interharmonics on the voltage peak fluctuation. However, high-frequency interharmonics have been shown to have significant effect on the flicker in the literature. This work combines the effect of both low- and high-frequency interharmonics on flicker, based on a voltage-peak-detection flickermeter algorithm. Using a spectral correction procedure applied during the flicker computation, the proposed flickermeter becomes also robust to fundamental frequency variations existing in power systems. The accuracy of the proposed flickermeter has been tested and proved by synthetic voltage data including fundamental frequency variations, harmonics and interharmonics around the fundamental as well as those at higher frequencies. The results obtained with field data obtained from electricity transmission network changes as whether considering flicker effects of high-frequency interharmonics or not. In high-frequency mode, including the effect of high-frequency interharmonics, the proposed method yields higher flicker values compared to the IEC flickermeter. In low-frequency mode, excluding them, both IEC flickermeter and the proposed flickermeter yield close flicker.