This study examined urban vulnerability in the three northeastern provinces of China—Heilongjiang, Jilin, and Liaoning—from 2000 to 2020, addressing challenges such as resource shortages, harsh environments, and inadequate education and healthcare. Using the weighted summation method and geographic detector model, this study analyzes the temporal and spatial evolution of urban vulnerability in 34 prefecture-level cities. The results show that overall vulnerability initially increased and then decreased, while economic vulnerability continued to rise. Spatially, vulnerability shifted from weak agglomeration to dispersion by 2020. Key drivers include new fixed assets, local fiscal revenue, and altitude. The findings highlight the need for tailored, coordinated development strategies to reduce urban vulnerability and promote sustainable regional growth, emphasizing the importance of balancing resources, environment, economy, society, and nature.