The paper deals with Nonlinear Energy Sinks (NES), utilizing piezoelectric transduction mechanism, focusing on the degree of effect the auxiliary nonlinear stiffness has on the performance of the NES and the performance of NES with the primary system subjected to random excitation. Hence, a parametric sweep of the auxiliary nonlinear stiffness over a broad range of values has been done and the variations in primary vibration suppression and voltage generation by the NES have been observed for its corresponding values. It has been conducted with the NES attached to a linear primary system and then an essentially nonlinear one. Comparison of results and validation of the performance of NES for both the cases have been performed. Following that, performance of the NES has been investigated when a linear primary system is subjected to random excitation. Two separate cases have been utilized to randomize the excitation. Results regarding vibration control and voltage generated have been derived for both and compared to those obtained for deterministic excitation. By and large, it is found that NES is successful in protecting a primary system and broadening the operation bandwidth, while satisfyingly generating voltage, irrespective of the type of excitation on the primary system. © 2021, Springer Nature Singapore Pte Ltd.