Base isolation is a widely researched, developed, and utilized passive control strategy for civil and mechanical engineering structures, acclaimed for its effectiveness and reliability. Despite the extensive and successful application of horizontal isolation devices in full-scale civil engineering structures, vertical isolation remains relatively uncommon, even though the vertical seismic component is particularly hazardous in near-fault zones. This paper presents preliminary results from an experimental campaign aimed at dynamically characterizing an innovative Quasi-Zero Stiffness (QZS) vertical isolation system. The system tested comprises three identical QZS devices, each designed to statically support the designated payload and dynamically isolate it through an engineered combination of vertical and horizontal springs. The experiments were conducted at the Experimental Dynamic Laboratory of the L.E.D.A. Research Institute, employing stepped sine, swept sine, and natural seismic tests to determine the dynamic properties of the isolation system, varying the payload mass and the horizontal stiffness preload. The findings, in terms of acceleration and displacement of the isolated mass, affirm the efficacy of the proposed QZS isolation system. Additionally, the device’s robustness is evidenced by its proficient non-linear filtering performance in response to seismic inputs of varying amplitude, frequency content, and non-stationarity.