Vegetation photosynthesis plays a crucial role in maintaining regional ecological balance and climate stability, holding significant implications for understanding the health of regional ecosystems and addressing climate change. This study utilized GOSIF data to analyze the spatio-temporal patterns and underlying causes of vegetation photosynthesis in the Yellow River Basin from 2001 to 2021. The results indicate that: (1) Overall, vegetation photosynthesis in the Yellow River Basin exhibits an increasing trend, with a spatial distribution characterized by higher values in the west and southeast, and lower values in the north. However, regions such as the Guanzhong Plain, the Amne Machin Mountains, the Ningxia Plain, and the Yellow River Delta show a notable degradation in vegetation photosynthesis. (2) Attribution analysis reveals significant variations in the impact of different climate factors on vegetation photosynthetic dynamics. Precipitation and solar radiation are positively correlated with vegetation photosynthetic dynamics in the Yellow River Basin, while temperature shows a negative correlation. Climate change and human activities exert varying degrees of influence on vegetation photosynthetic dynamics in the Yellow River Basin, with human activities contributing significantly more (76.24%) than climate change (23.76%). In the degraded areas, climate change plays a greater role in the contributions to vegetation dynamics in sparse grasslands and farmland, while human activities contribute more in shrublands, grasslands, and wetlands. In forest areas, the contributions of climate change and human activities are relatively equal. The findings of the study contribute to a better understanding of the mechanisms driving changes in vegetation photosynthesis in the Yellow River Basin, providing important references for ecological conservation, sustainable development, and climate change research in the region.