‘KM3’ is an F1 hybrid maize developed by the maize breeding team at the National Institute of Crop Science (NICS), Rural Development Administration (RDA), for the Southeast Asian seed market. This hybrid was obtained by crossbreeding two inbred lines—14K26 and 15VL027. The hybrid was evaluated in a crop-year yield trial in Cambodia, followed by country adaptability trials in Cambodia and Indonesia in 2016 and 2017, respectively. The flint-like seed type of ‘KM3’ makes it suitable for both food and feed, demonstrating its adaptability to Southeast Asia. ‘KM3’ exhibited early maturity, high grain yield as an F1 hybrid, and resistance to downy mildew. The silking date of ‘KM3’ was two days earlier than that of the leading cultivar ‘CP888’ in Cambodia, with a grain yield of 913 kg/10a, outperforming ‘CP888’ by 26% (Registration No. 9319).