This paper examines the association between the frequency of use of urban green spaces (UGS) and the subjective well-being (SWB) of Mexico City's residents during the COVID-19 pandemic. We conducted an online survey (N = 1954) regarding individuals' perceptions and use of UGS and their SWB, evaluated through the short version of the Warwick-Edinburgh mental well-being scale. Multilevel mixed-effects regression analyses were performed to investigate the association between the frequency of UGS use and SWB, including individual and municipal level characteristics as covariates. Our results suggest that respondents who used UGS once or more per week during the pandemic reported higher SWB scores (8.7%) than those with zero visits. These findings have public policy implications that could enhance the role of UGS in urban environments during times of crisis.