This article examines the effects of artificial light at night (ALAN) and near-surface air temperature (Ta) on vegetation phenology across 428 Northern Hemisphere cities from 2014 to 2020. Utilizing high-resolution datasets, including monthly ALAN images from the VIIRS DNB and daily near-surface air temperature data, the study defines vegetation phenology indicators such as the onset of greenness (SOS) and end of greenness (EOS) based on a structured analysis of various land cover types. By categorizing cities along rural-urban gradients and applying mathematical modeling to quantify relationships, the research highlights that ALAN significantly influences urban phenological shifts. The findings suggest an advancement in SOS and a delay in EOS, indicating that urbanization, characterized by increased ALAN and warmer temperatures, is extending growing seasons in urban areas compared to rural ones. Overall, this study underscores the intricate interplay between urbanization, climate factors, and vegetation responses.