Abstract: Evapotranspiration (ET), a core component of a regional hydrological cycle and ecosystem energy exchange, is of great significance for regional water resource management and ecological conservation. Based on MODIS ET products and by integrating trend analysis and contribution rate analysis, this study explored the spatiotemporal variation trends and driving mechanisms of ET in Guangdong Province from 2000 to 2024. The results indicate that during the study period, the ET in Guangdong varied significantly in spatial distribution, ranging from 638.77 mm/a to 1 750.56 mm/a. Furthermore, it was higher in the east and north and lower in the west and south. In terms of seasonal dynamics, the ET distribution followed a unimodal pattern, with summer time, from May to September, contributing over 55% of the annual ET and winter exhibiting the minimum value. Over the past more than two decades, the ET across the province generally presented an upward trend with fluctuations, with a growth rate of 5.287 mm/a. Increases in ET primarily occurred in parts of Zhaoqing, Yunfu, and Chaozhou cities, while decreases in ET were observed in most areas of both the urban agglomeration of the Pearl River Delta and Shantou City. Among various land use types, forest land served as the most significant ET contributor (average annual ET: 1 130.25 mm/a, accounting for over 60%), followed by cropland (over 20%) and construction land (approximately 5%). Regarding driving factors, human activities exerted regionally varying influence, promoting and inhibiting ET in parts of eastern Guangdong and the Pearl River Delta, respectively. Contribution rate analysis reveals that 83.77% of increases in regional ET were jointly driven by climate change and human activities. Compared to climate change, human activities contributed more significantly to ET, with areas where human activities contributed over 80% of ET being concentrated in the coastal areas of eastern Guangdong and the central Leizhou Peninsula. The results of this study will help gain deep insights into the ET patterns in Guangdong Province, thereby providing a scientific basis for the rational utilization and conservation of regional water resources.