The spatiotemporal evolution patterns of cultivated land in the Jinsha River dry-hot valley are explored. Multi-source remote sensing data from 1990 to 2023 were utilized. The land use transfer matrix, Cultivated Land Elevation Index of Heterogeneity (CEIH), and distance-to-river gradient zone analysis were applied. The vertical and horizontal migration characteristics of cultivated land were systematically analyzed. Three stages of cultivated land change are observed during 1990–2023. These stages are characterized by stability, reduction caused by the Grain-for-Green Program, and continuous expansion. The late-stage expansion is mainly driven by the conversion of grassland and shrubland. A peak cultivated land area of 5034.7 km2 is reached in 2021. Vertically, cultivated land expansion is concentrated in the middle-altitude zone of 1300–2000 m. Horizontally, the distribution center of cultivated land is continuously shifted away from rivers. The median distance is cumulatively increased by 631 m. A spatial pattern of near-river shrinkage and distant-river expansion is exhibited. Typical patterns of land-use evolution and agricultural structure adjustment in the dry-hot valley region are systematically revealed. Scientific support is provided for the rational spatial allocation of soil and water resources. Sustainable agricultural development in the study area and similar arid and semi-arid valley regions is further promoted.