The existing medium height structures (ES) may be retrofitted with tuned sloshing water dampers (TSWD), for mitigating increased seismic demands. The performance of the TSWD as response reducing device against vibratory loads has been investigated through shake table tests, in coupling with scaled model(SM) of ES. The optimum coupling parameters of the TSWD with respect to SM have been obtained through free vibration tests. Subsequently the optimally tuned SM-TSWD coupling has been subjected to forced sinusoidal vibration of the resonant frequency. The effectiveness of the retrofitting regime has also been tested against ground motion time histories. The experimental data have been analytically extrapolated for application to the real life existing structure (ES). A response reduction of the order of 25% has been predicted for the ES with 1.5% mass ratio. A seismic retrofitting design methodology of ‘hardware interactive soft path’ for assured displacement response reduction has been devised.