Reliability analyses on various control devices are of vital importance in examining and quantifying their practical feasibility and effectiveness. In specific, an emerging base isolation technique using a tuned inerter damper (TID) draws researchers’ attention given some of its unique merits, such as the compact damper size, lightweight, and the fact that it will not compromise structural stiffness when the system is static and thus prevents the long-term creeping issue. To justify its feasibility and robustness in face of random earthquake excitations, this paper presents both (1) a simulation-based stochastic dynamic response analysis, and (2) a reliability analysis of a benchmark reinforced concrete (RC) structure with a TID isolation layer. It is found that although seismic randomness shall substantially affect the structural dynamic responses, the introduction of a TID isolation layer to the structure will significantly alleviate this effect and subsequently enhances the overall system robustness, which can be parallelly identified from the notable different features between their corresponding probability density evolutions. In addition, the reliability of the RC structure is also drastically improved owing to the introduction of the TID isolation layer, which highlights its effectiveness and sheds light on its great potential in future industrial applications.