In this paper, we consider simultaneous information and energy transfer in millimeter Wave (mmWave) unmanned aerial vehicle (UAV)-assisted cellular networks, in which the user locations are modeled as a Thomas cluster process. Distinguishing features of mmWave communications, such as different path loss models for line-of-sight (LOS) and none-LOS (NLOS) links and directional transmissions, are taken into account. Initially, we characterize the complementary cumulative distribution functions (CCDFs) and the probability density functions (PDFs) of the distances from the typical user equipment (UE) to its own cluster center UAV, other Poisson point process (PPP) distributed UAVs and the ground base stations (GBSs). The association probability, energy and signal-to-interference-plus-noise ratio (SINR) coverages of different tier UAVs and GBSs are investigated. Moreover, we define a successful transmission probability to jointly present the energy and SINR coverages and provide general expressions. Through numerical results, we investigate the system coverage performance.