This study investigates the recombination dynamics in highly mismatched ZnTeO alloys using time-resolved photoluminescence (PL) spectroscopy. The large PL energy redshift with increasing O content and the disappearance of the ZnTe emission verify the O-induced conduction band anticrossing effect. The incorporation of O generates electron localization below the E- conduction subband tail, which provide additional optical transitions and cause complex recombination mechanisms. Photoexcited free electrons in both the E + and the E- conduction subbands favor rapid relaxation to low energy states. Additionally, temperature-independent long carrier lifetimes (>130.0 ns) that are induced by localized electrons increase with O concentration.