Abstract <p>In this study, the impacts of viscosity and pores on the damped vibration characteristics of the functionally graded beams resting on viscoelastic foundations are examined. The proposed viscoelastic foundation consists of four parameters that include two elastic parameters and two viscous coefficients, making it suitable for modelling the complex interactions between structures and foundations. Several pores’ distributions including even and uneven, V-, A-, O-, and X-porosity distributions are used to take into account the porosity effects. The parametric study is carried out to illustrate the influence of some parameters on the damped vibration response of functionally graded porous beams. The results of this study showed that porosity and viscosity have significant effects on the damped vibration properties of the functionally graded beams. This can serve as a reference point for the design, testing, and optimization of the beams in engineering applications.</p>