Research indicates that women and girls face gender-specific stressors related to sanitation that affect their mental health, and women's decision-making agency may play a role in this relationship. This study aimed to quantitatively assess the association between women's sanitation-related decision-making - overall, within the household, and within the community - and well-being in two urban municipalities in Bangladesh. This paper is a secondary analysis of cross-sectional survey data collected from 1449 women in Meherpur and Saidpur, Bangladesh from March-April 2022. We measured well-being using the World Health Organization Well-being Index [WHO-5] and primary exposures included women's sanitation-related decision-making and access to an unshared latrine. Decision-making was measured using the Agency, Resources, and Institutional Structures for Sanitation-related Empowerment (ARISE) scale; the full-scale score was utilized in the first analysis and the five individual factor scores were used in the second. Linear regression models were employed to assess the associations between decision-making and well-being scores, controlling for life stage, socioeconomic level, perceived social support and self-reported physical health. Analyses were conducted with city as a fixed effect and also stratified by city. Mean well-being scores were moderate in both cities, with approximately 20 % of respondents reporting poor well-being. On average, women generally agreed that they had a role in sanitation-related decision making (mean score = 2.66 on a 1-4 scale, with higher scores indicating stronger agreement that they had the ability to make sanitation-related decisions). In the full models using the full decision-making scale score, results indicated a positive association between the overall decision-making scale score and well-being (β = 0.73, p = 0.02). In full models using decision-making factor scores, we observed a positive association between well-being and individual decision-making factor scores for the ability to influence community-level sanitation decisions (β = 1.10, p = 0.0002) and to make small household sanitation decisions (β = 1.07, p = 0.006). Conversely, the ability to participate in community-level sanitation decisions was negatively associated with well-being (β = -0.68, p = 0.02). The ability to participate in household sanitation decisions and make large household sanitation decisions were not associated with well-being. Access to an unshared latrine was not associated with well-being in fully adjusted models. The relationships between decision-making factors and well-being varied in analyses stratified by city. Women's involvement in sanitation-related decision-making likely varies based on the extent of their participation, the nature of the decisions, and a range of contextual and household- or individual-level factors (e.g., socioeconomic level, age, education). To effectively improve women's well-being, sanitation programs must be informed by context-specific research exploring sanitation-related decision-making and its mediators among the populations of interest.