Drought and salinity are two major environmental factors that severely limit plant growth and development. MYB functions as a transcription factor that is crucial in how plants respond to stress from adverse conditions. In this study, we identified a gene encoding Populus simonii × P. nigra MYB (v-myb avian myeloblastosis viral oncogene homolog) transcription factor, whose transcription level was significantly induced under salt stress and osmotic stress. Subcellular localisation results showed PsnMYB30 was located in the nucleus. Yeast one-hybrid assay indicated the gene exhibited transcriptional activation activity and it can precisely bind to the G-box elements. Under normal growth conditions, there were no significant differences in physiological and biochemical indicators between wild-type and transgenic tobacco. However, under salt and drought stress, transgenic tobacco overexpressing PsnMYB30 exhibited superior root length and fresh weight compared to the wild-type (WT), with higher levels of SOD, POD, proline, and chlorophyll content, and significantly lower MDA and H₂O₂ content than the WT. These findings indicate that PsnMYB30 significantly enhances the salt tolerance and drought resistance of transgenic tobacco. These results indicate that PsnMYB30 is a key target gene for studying salt-tolerant and drought-resistant plants in genetic breeding.