Timber-concrete composite (TCC) floor systems have gained interest as a sustainable alternative to concrete floors, particularly in applications requiring longer spans than typical timber floor systems. By connecting timber elements to concrete slabs with shear connectors, TCC systems increase the structural stiffness and improve vibrational characteristics while maintaining a reduced carbon footprint. This study investigates the dynamic performance of a 6 m span glued-laminated timber-concrete composite (GLTCC) floor by means of forced vibration testing and finite element (FE) simulations. Experimental results revealed a first natural frequency of 13.25 Hz, surpassing the 8 Hz requirement specified in Eurocode 5, and a damping ratio of 3.34% for the first mode – close to recommended values for TCC floors with a floating screed. The FE model closely predicts the experimentally measured frequencies and mode shapes, demonstrating the validity of the numerical approach. Parametric studies further highlight the importance of support conditions and connection properties. Continuous supports such as walls or sufficiently stiff beams help maintain higher frequencies, while column supports reduce the frequency in certain modes. Enhanced connection stiffness, as achieved by notches, raises the overall dynamic response, whereas less stiff alternatives, such as screws, lead to reduced composite action and lower frequencies. Overall, these findings confirm the effectiveness of GLTCC floor systems for medium-span applications and highlight the need for careful consideration of support conditions and connection details to ensure optimal vibrational performance.