The effectiveness of a novel semi-active variable stiffness tuned mass damper (SAIVS-TMD) for response control of wind excited tall benchmark building is investigated in this study. The benchmark building considered is a proposed 76-story concrete office tower in Melbourne, Australia. It is a slender building 306 meters tall with a height to width ratio of 7:3; hence, it is wind sensitive. Across wind load data from wind tunnel tests are used in the present study. The objective of this study is to evaluate the new SAIVS-TMD system, which has the distinct advantage of continuously retuning its frequency due to real time control; hence, the system is robust to changes in building stiffness and damping. In com- parison, the passive tuned mass damper (TMD) can only be tuned to a fixed frequency. Time varying analytical model of the tall building with the SAIVS-TMD is developed. The frequency tuning of the SAIVS-TMD is achieved based on Empirical Mode Decomposition and Hilbert transform instantaneous frequency algorithm developed by the authors. It is shown that the SAIVS-TMD can reduce the struc- tural response substantially, when compared to the uncontrolled case, and it can reduce the response further when compared to the case with TMD. Additionally it is shown the SAIVS-TMD reduces re- sponse even when the building stiffness changes by §15% and is robust; whereas, the TMD loses its effectiveness under such building stiffness variations. It is also shown that SAIVS-TMD can reduce the response similar to an ATMD; however, with an order of magnitude less power consumption.