Foxtail millet (Setaria italica), a significant food crop in arid and semi-arid regions, exhibits remarkable drought tolerance. Investigating the genes involved in the drought stress responses of foxtail millet is crucial. In this study, we identified an R2R3-MYB transcription factor gene from foxtail millet, designated SiMYB52. SiMYB52 was localized to the nucleus and demonstrated transcriptional activation activity in yeast. Arabidopsis plants overexpressing SiMYB52 exhibited enhanced tolerance to drought stress compared to wild-type plants. Under drought conditions, the overexpression of SiMYB52 led to elevated transcript levels of genes associated with sulfate absorption (AtSULTR1;1 and AtSULTR1;2) and augmented activities of key enzymes involved in sulfur assimilation, including ATP sulfurylase (ATPS), sulfite reductase (SiR), and O-acetylserine(thiol)lyase (OASTL). This resulted in increased cysteine (Cys) and glutathione (GSH) content within the leaves of transgenic Arabidopsis. Furthermore, leaves from Arabidopsis overexpressing SiMYB52 displayed significantly higher activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), and glutathione reductase (GR) compared to those from wild-type plants. This enhancement, along with elevated GSH levels, contributed to more effective scavenging of reactive oxygen species (ROS) induced by drought conditions in the leaves of transgenic plants. Moreover, silencing of SiMYB52 resulted in decreased tolerance to drought stress in foxtail millet when compared to wild-type plants. The SiMYB52-RNAi foxtail millet demonstrated reduced sulfur assimilation and impaired antioxidant defense under drought conditions. This study provides a theoretical foundation for understanding the molecular mechanisms underlying the drought response in foxtail millet.