The Yellow River Basin, a critical water-bearing region in China, is facing increasingly prominent conflicts between water supply and demand. Based on Maslow’s hierarchy of needs theory, this study categorizes the socio-economic water use in the Yellow River Basin into three levels: rigid water use, semi-flexible water use, and flexible water use. Furthermore, the concept of bottom-line water use is proposed to ensure basic water security under extreme drought conditions. By constructing a water resources allocation model and using the actual water usage data from 2022 as the baseline, this study simulates the supply–demand responses under different water inflow scenarios and identifies the critical thresholds for water supply–demand imbalance in the Yellow River Basin. The results indicate that when the minimum natural water inflow of the Yellow River is 30.8 billion m3, the system is in a state of severe imbalance, with an associated economic loss of 259.27 billion CNY. An inflow of 44.6 billion m3 corresponds to a moderate-severe imbalance, 52.6 billion m3 to a moderate imbalance, and 56.2 billion m3 to a mild imbalance. The findings of this study can provide a scientific basis and decision-making support for precise regulation, risk warning, and sustainable utilization of water resources in the Yellow River Basin.