<p>To resolve the inherent contradiction between low-frequency vibration isolation and the deterioration of high-frequency transmissibility, a quasi-zero-stiffness (QZS) vibration isolator with composite segmented damping and stiffness is proposed. A dimensionless nonlinear dynamic model of the system is established. The approximate analytical solutions for the primary resonance response are derived via the averaging method, and the stability conditions for the steady-state solutions are determined based on the Routh-Hurwitz criterion. The accuracy of the theoretical analysis is verified through numerical simulations. With a focus on the impacts of segmented parameters on the system’s dynamic evolution, the intrinsic trade-off between rigid amplitude-limiting capacity and force isolation performance arising from the segmented stiffness is elucidated. Crucially, the introduction of segmented damping is found to effectively reconcile this conflict, suppressing nonlinear jump phenomena and chaotic behaviors, while the segmented gap functions as a threshold switch. Furthermore, the mechanisms of nonlinear jump and grazing-induced impact are unveiled, and a design criterion for parameter jump avoidance is established. Analysis based on the principle of energy conservation demonstrates that strong segmented damping can induce an amplitude locking effect, realizing a transition of vibration energy from passive dissipation to source energy decoupling and inherent self-regulation. By virtue of the synergistic mechanism of rigid amplitude limiting and flexible energy dissipation, the proposed QZS isolator significantly enhances low-frequency isolation performance and stability while maintaining superior high-frequency isolation performance, providing theoretical support for the optimal design of nonlinear vibration isolators.</p>