<p>The low-carbon city pilot policy (LCCP) is an important policy for the low-carbon transition of cities. Residents, as an important part of the city, their welfare performance is an important aspect to measure the degree of urban low-carbon transition and to test the effectiveness of the implementation of low-carbon city pilot policy. This paper selects panel data of 237 cities from 2006–2019 and uses LCCP as a quasi-natural experiment. The multi-period difference-in-differences (DID) model is used to empirically analyze the impact of urban low-carbon transition on residents' welfare. It is found that LCCP can significantly improve the level of residents' welfare, and this conclusion still holds after a series of robustness tests. The analysis of the mechanism of action shows that LCCP enhances residents' welfare by promoting urban employment, increasing government investment in environmental governance, improving urban innovation capacity and increasing urban green space. Heterogeneity analysis shows that at the city level, LCCP significantly improves the welfare of residents in the eastern region, non-resource cities, high-carbon emission cities and cities with higher levels of financial development; and at the resident level, the welfare level of residents is significantly improved regardless of whether they are sensitive to LCCP or not. It is further found that command policy instruments and market policy instruments are the main instrumental means for LCCP to promote residents' welfare levels. This paper analyzes the impact of LCCP on residents' welfare from a micro perspective, broadens the assessment of the effects of LCCP, and provides policy insights and practical references for the enhancement of residents' well-being and the implementation of urban low-carbon transformation.</p>