Carbon nanotubes (CNTs) have been suggested to be reinforcement fillers in a variety of composite materials due to their exceptional electrical, thermal and mechanical properties. In terms of thermal properties, incorporating CNTs into a polymer matrix should increase the effective thermal conductivity of the resulting composite. However, the presence of resistance to the transfer of heat at the CNT-polymer interface, known as the Kapitza resistance, results in underperformance of CNT nanocomposites, in terms of thermal properties. In this work, we use Monte Carlo simulations to calculate the effective thermal conductivity of CNT nanocomposites taking into account the Kapitza resistance, as well as the effective thermal conductivity for different inclusion geometries (sphere, cylinder and parallelepiped). The effect of the dispersion pattern of the nano-inclusions is also investigated. Finally, comparing the calculated thermal conductivity from the simulations to experiments, the methodology can be used to calculate the Kapitza resistance of such systems.