In the present paper, a multiscale technique is developed to evaluate the mechanical vibration behavior of laminated nanocomposite beams under hygrothermal stresses. The study determines the mechanical properties of the carbon nanotube-based matrix, through the modified Halpin-Tsai model, which is incorporating the impact of carbon nanotube (CNT) orientation, curvature and aggregation, as well as CNT size. In addition, the Chamis micromechanical equations are utilized to assess the six elastic constants of the hybrid nanocomposite lamina, examining hygrothermal characteristics, including humidity and temperature. Finally, finite element method is employed to evaluate the vibration behavior for neat and CNT-based laminated composite beams. The investigation explores various parameters involved in the design process, such as the impact of CNT microstructural characteristics and environmental factors on the vibration performance of nanocomposite beams. The findings of the present multiscale modeling framework conform to data from experiments, available in open literature. It could be assumed that while CNT inclusion enhances the elastic properties of the hybrid composite lamina, the vibrational frequency of the composite beams is influenced by the temperature and moisture variations. In addition, CNT microstructural characteristics remain of critical concern in the design of effective nanocomposite structures. The present multiscale modeling procedure could be a beneficial tool in optimization of CNT-reinforced composite structures for future industrial applications.