The spatiotemporal heterogeneity of urban vegetation phenology (UVP) has intensified due to coupled urban expansion and climate change, yet the systematic understanding of UVP responses along urban-rural gradients across diverse climatic contexts and urban expansion remains limited. Therefore, this study selected 31 Chinese cities across diverse climate zones and city sizes using multi-source remote sensing data (2001-2020) to quantify the synergistic effects of urban expansion and climate change on urban-rural UVP differences (Delta UVP). First, UVP in China exhibited advanced start of growing season (SOS), delayed end of growing season (EOS), and extended length of growing season (GSL), with more pronounced shifts in southeastern regions compared to northwestern zones. Furthermore, the magnitudes of SOS advancement, EOS delay, and GSL extension gradually decreased along the urban-rural gradient. Delta UVP in large cities was smaller than that in other city sizes, whereas arid and semi-arid zones exhibited significantly greater Delta UVP than humid and semi-humid zones. Second, Delta SOS, Delta EOS, and Delta GSL demonstrated predominantly negative, positive, and positive correlations with both urban heat island intensity (Delta LST) and urban expansion intensity (Delta ISP), respectively. Medium cities demonstrated the maximum response magnitudes of Delta UVP to Delta LST compared to other city sizes, whereas small towns demonstrated the maximum response magnitudes of Delta UVP to Delta ISP. The response magnitudes of Delta UVP to both Delta LST and Delta ISP were significantly greater in arid and semi-arid zones than in humid and semi-humid zones. Finally, principal component analysis confirmed that urban factors predominantly drive Delta UVP variations, with Delta ISP identified as the primary regulatory factor. These findings provide critical insights into urban vegetation dynamics under rapid expansion and climate change.