Using a large-scale pilot test on time-of-use (TOU) pricing for residential customers, this study analyzes the effects of TOU pricing on the load patterns of residential customers and on producer surplus in South Korea. We estimate the difference in the electricity demand functions of residential customers across peak, intermediate, and off-peak periods before and after TOU pricing. In addition, we assess the supply curve in the wholesale electricity market and calculate the changes in electricity purchase costs by integrating the supply curve over the range of consumption changes across the periods. This study simulates the effects of TOU pricing on producer surplus that would be obtained if all residential customers in South Korea switch from increasing block pricing to TOU pricing. Our results show that TOU pricing can be an effective measure for load transfer and simultaneously increase producer surplus. We find that although the revenue of electric utility generally decreases, the cost savings are greater and thus producer surplus increases. The results can be a valuable reference for the South Korean government regarding the nationwide expansion of TOU for residential electricity in the future.