The optimal design of inertial amplifier base isolators (IABI) for dynamic response mitigation of multi-storey buildings subjected to base excitations has been studied in this paper. In order to achieve the closed-form expressions for optimal design parameters of IABI, [Formula: see text] optimization method has been employed. The effectiveness of the closed-form expressions for optimal design parameters was evaluated by determining the isolated structures’ frequency and time domain responses and comparing them to the corresponding responses obtained from equivalent uncontrolled structures. A numerical study employing the Newmark-beta method is conducted to obtain time-domain responses using near-field earthquake base excitation. The response reduction capacity (%) of the optimum inertial amplifier base isolator is compared to the response reduction capacity (%) of the optimum traditional base isolators, demonstrating that inertial amplifiers have increased the vibration reduction performance of traditional base isolators by 50% to 60%. All the outcomes from the study are mathematically accurate and also feasible for practical design purposes.