The Amazon–Cerrado transition region has a high rate of deforestation for agriculture, livestock, logging, and for the increase in urban areas of cities. The development of cities in this region in recent decades has increased the deforestation process and modified the local microclimate and the exchange of energy and water between the surface and the atmosphere. However, the magnitude of the change in energy and water exchanges due to urbanization is unknown for most Brazilian cities, especially in the Amazon–Cerrado region. Thus, the objective was to evaluate the spatiotemporal change in energy balance and in evapotranspiration (ET) patterns over three decades of urbanization in Sinop. The surface energy balance (SEB) and ET were estimated by the SEB algorithms for land with Landsat 5 Thematic Mapper images from the Sinop region, Mato Grosso, Brazil, in 1985, 2000, and 2010. The estimated SEB and ET were validated with measurements in a flux tower in the Amazon–Cerrado transition forest 50 km from the urban area of Sinop. The components of the SEB, except the soil/storage heat flux (G), had a strong correlation, and the ET had a moderate correlation with measurements in the flux tower. The surface albedo (a_sup), land surface temperature (LST), sensible heat flux (H), and G of the study area increased over the years, while the normalized difference vegetation index, latent heat flux (LE), and ET decreased over the years. Buildup and grassland areas had lower values of NDVI, Rn, LE, and ET and higher values of a_sup, LST, H, and G than forest areas. Therefore, the urbanization of Sinop has decreased available energy for ET and increased the energy to heat the air and soil.