Miscanthus, a perennial grass, is renowned for its remarkable tolerance to abiotic stress. Excessive levels of drought severely impair plant growth and yield. Plant nuclear factor Y (NF-Y) transcription factors (TFs) play pivotal roles in regulating responses to drought stress in species such as Arabidopsis and maize. However, their functional roles in conferring drought tolerance in Miscanthus remain largely unexplored. This study’s genome-wide analysis and gene expression profiling of Miscanthus under dehydration/osmotic stress identified a transcription factors gene, MsNF-YA4, which was significantly upregulated under dehydration/osmotic stress. MsNF-YA4 overexpression in Arabidopsis significantly enhanced drought tolerance, leading to increased transcription of stress- and antioxidant enzyme-related genes. Compared with the wild type (WT), the transgenic lines exhibited markedly higher relative water content (RWC), chlorophyll content, proline level, and antioxidant enzyme activity. Furthermore, the MsNF-YA4/MsNF-YB3/MsNF-YC2 improved the transactivation of the Miscanthus P5CS1, SOD (Cu/Zn) and CAT1 promoters in the transient system. These results offer fresh perspectives on the role of Miscanthus NF-YAs in drought tolerance and offer promising genetic resources for developing drought-tolerant crops through breeding programs.