In coalbed methane (CBM) reservoirs, permeability changes dynamically throughout the life of the reservoir as the pressure depletes due to production. The dynamic variation of coal permeability mainly depends on the combined effect of effective stresses and coal matrix shrinkage caused by gas desorption. Under the conditions of pressure-dependent diffusivity in coal reservoirs, the flow mechanism in CBM reservoirs complicates the solution of the two-phase diffusivity equation. In this study, the authors present a new approach to describe the CBM reservoir diffusivity equation in a form that fully couples the pressure-dependent diffusivity and time-dependent desorption effects in the transport mechanism of CBM reservoirs. This paper presents a semi-analytical solution of the fully coupled diffusivity equation under pseudo-steady state flow conditions. The proposed solution is then leveraged to predict the performance of a two-phase CBM well using an approach that is alternative to the conventional method for CBM reservoirs. The proposed semi-analytical model presents a computational method not only to predict the performance but also to evaluate the performance of a producing CBM well. The model presented in this study has been used to investigate the impact of pressure-dependent diffusivity and time-dependent desorption on the production behavior of CBM wells producing under pseudo-steady state conditions. The results of the semi-analytical solution have been verified using numerical simulator CMG-GEM as well as actual in-field data.