Based on prefecture-level data from China over the period 1999–2018, our study aims to identify the impact of urban land expansion on economic growth conditional on the spatial population distribution within a city. Controlling the potential path dependence impact of the urban economy with a lagged explanatory variable in the designed model, and primarily based on the generalized method of moments, the empirical results show that it is the relative urban land expansion rather than the net expansion that is disadvantageous to urban economic growth. The interior spatial population distribution, which is primarily measured as the relative proportion of the population residing outside the main urban area, boosts urban economic growth directly as well as promoting it indirectly by alleviating the negative impact of urban relative land expansion. Our results provide a theoretical basis for alleviating the population–land contradiction and reducing the risk of urban economic growth.