Ordos city is a key area in the ecological restoration efforts of the Yellow River "Ji"-shaped bend region and plays a vital role in strengthening the ecological barrier in the arid and semi-arid areas of northern China. Vegetation dynamics are an important indicator of the effectiveness of regional ecological restoration. However, the relative contributions of climate change and human activities to the spatiotemporal dynamics of vegetation cover during the growing season in Ordos remain unclear. Based on MODIS satellite data from the Google Earth Engine (GEE) platform, this study analyzed the spatiotemporal variations of the Normalized Difference Vegetation Index (NDVI) in Ordos during the growing seasons (from June to September) from 2000 to 2020. To quantify the responses of climate change and human activities, Theil-Sen median trend analysis, Mann-Kendall significance test, partial correlation, and residual analysis were applied. The key findings showed that: (1) Temporally, the growing season NDVI in Ordos showed a fluctuating upward trend from 2000 to 2020, with an average increase rate of 0.005/a, and more notable vegetation improvement during 2011-2020. Spatially, NDVI exhibited significant regional differences, with higher values in the eastern part compared to the western part. (2) Precipitation and temperature exerted varying degrees of influence on vegetation during the growing season. The area exhibiting a positive correlation between cumulative growing-season precipitation and NDVI accounted for as much as 98.08% of the total study region, with 47.08% of these areas being significantly influenced by precipitation (P < 0.05). This demonstrated that precipitation served as the primary climatic driver of vegetation dynamics during the growing season. (3) Residual trend analysis revealed that over the past 21 years, human activities have generally exerted a positive impact on vegetation during the growing season, with positively correlated areas accounting for approximately 86.12% of the study area. Overall, from 2000 to 2020, the contribution rates of climate change and human activities to NDVI changes were 25.87% and 73.66%, respectively, suggesting that human activities were the dominant factor. (4) The contributions of climate change and human activities exhibited significant spatial heterogeneity. Climate change primarily contributed lowly to moderately, with high-contribution areas (>60%) concentrated in the western region, accounting for approximately 6.30% of the total area. In contrast, human activities mainly contributed highly with high-contribution areas (>60%) primarily distributed in the eastern region, covering about 80.06% of the total area. This indicated that the spatial heterogeneity pattern of driving NDVI changes during the growing season in Ordos showed an 'eastern human-western climate’ distribution.