Semi-active control systems having the adaptability aspects of active control methods along with the reliability and stability of passive controllers have been recently used to control structures against natural hazards. In this paper, a fuzzy logic based controller is designed to attenuate vibrations of a tall building under cross wind excitations. The building considered is the benchmark 76-story reinforced concrete office tower proposed for the city ofMelbourne,Australia. A collection of semi-active dampers is used at the first story to apply control forces to the structure where the damping is found through the fuzzy logic controller. Higher levels of performance are achieved in mitigating structural responses, especially the average RMS displacement response through the application of the fuzzy controller. Also investigated in the present study is the robustness of the whole structure-controller system to uncertainties in the stiffness matrix in the form of multiplicative perturbations. Simulation results verify the superior performance of the semi-active fuzzy controller over the passive controller in response mitigation of the perturbed structure.