The economic dispatch problem is a very important and fundamental topic in the economic opera-tion of power system, emphasizing the efficient allocation of generation resources to minimize fuel costs while satisfying demand and adhering to different operational constraints. Since its introduction, many of the optimization methods, techniques, and algorithms have been applied to solve this complex and nonlinear hard-problem. This research introduces the wild horse optimizer algorithm (WHOA), as a new metaheuristic optimization technique, for efficient solving of the economic dispatch (ED) problem, which includes various equality and inequality constraints, such as prohibited operating zones (POZ), valve-point loading effects (VPLE), and ramp rate limits (RRLs) of thermal power plants in the presence of transmission power losses. The effectiveness of the mentioned technique is validated through implementation it on four different case studies comprising 6, 15 ,40 and 140 generating units in terms of obtained results. The simulation results of quadruple test cases confirm the WHOA ability in reducing the best previous operation costs of RCBA, emended salp swarm algorithm (ESSA), new PSO- simple local random search (NPSO-LRS), and modified MTS (MTLA) algorithms, by at least 0.0423 %, 0.0101%, 0.040054%, and 0.12839 %.