The bat algorithm (BA) is a population-based optimization that mimics the echolocation of microbats when looking for prey and avoiding obstacles. BA is a unique algorithm that gives fast convergence and optimum solutions to a problem. Reactive power dispatch (RPD) plays a vital role in the control and operation of the power system and is part of the optimal power flow (OPF) problem. It is formulated as continuous and discrete (i.e., mixed integer nonlinear programming) model. This research involves the application of BA to RPD to reduce power loss (PL) in transmission systems and applied constraints handling (penalty function) to keep it within the operating limits. Also, the optimum control settings are voltage of the generator, reactive power sources, and transformer taps were obtained without violating the limits. The method's performance was demonstrated on standard IEEE New England 39 and 57 node systems. BA can reduce the test systems’ losses to 37.109 MW and 22.304 MW from the initial case of 43.6 MW and 28.46 MW, respectively. The percentage savings of the test systems are 14.94% and 21.63%, respectively, which shows that BA can reduce PL in electrical power systems. The simulation results of BA are compared with the other techniques, and BA outperformed them.