With the continuous advancement of the automotive industry, users’ demands for vehicle ride comfort are constantly increasing. Low-frequency vibrations, characterized by their strong penetration and difficulty in attenuation, significantly impact ride comfort and represent a key challenge in current NVH research. Quasi-zero stiffness (QZS) structures demonstrate exceptional performance in low-frequency vibration isolation, making them widely adopted in automotive and industrial systems. However, traditional QZS structures predominantly rely on the parallel connection of positive and negative stiffness elements, presenting drawbacks such as stringent stiffness matching requirements and limited design freedom. This paper proposes a tandem-connected Oblique-Arch-Oblique (OAO) QZS structure based on a nonlinear deformation mechanism. By introducing symmetric nonlinear deformation, the structure effectively expands the operational range of conventional QZS systems and overcomes stiffness matching challenges. Firstly, the mechanical characteristics and key geometric parameters of the OAO structure were analyzed using the energy method. Secondly, finite element simulations validated the influence of critical parameters and demonstrated the design flexibility of the OAO structure in terms of load-bearing capacity. Finally, vibration isolation experiments were conducted to evaluate its low-frequency isolation performance. The results confirm that the proposed OAO structure achieves both a wide operational range and excellent low-frequency vibration isolation, validating it as an innovative structural solution for low-frequency vibration mitigation.