Cognitive factors can strongly influence mothers' well-being. Maternal beliefs about societal expectations, role identity, maternal confidence, and concern about being a good or bad parent threaten maternal well-being, especially if these beliefs are irrational, inflexible, and strict. Moreover, they can negatively influence the critical time of returning to work after maternity leave. As stated by the conservation of resources theory, people may become more irrational when their resources are exhausted, with detrimental effects on individual well-being. To protect and enhance well-being, working mothers should draw upon additional resources, including their organizational contexts. In this regard, a key figure is the supervisor, whose positive behaviours and stable support can improve working mothers' well-being and facilitate their effective return to work after maternity leave. This study aims at examining the relation between the rigidity of maternal beliefs and well-being (namely, general health, job satisfaction, and job performance), hypothesizing the mediation effect of perceived supervisor support during return to work after maternity leave. The Rigidity of Maternal Beliefs Scale, the measure for Supervisors to Support Return to Work, and the General Health Questionnaire were used together with a two-item measure for examining job performance and a single-item measure for measuring job satisfaction. The questionnaire was completed by 216 mothers. We tested the hypotheses by means of structural equation models with latent variables, using the Lisrel 8.80 software. Findings show that rigidity of maternal beliefs is associated with perceived supervisor support during return to work, which, in turn, is associated with working mothers' general health, job satisfaction, and job performance. Consequently, perceived supervisor support during return to work totally mediates the relations between the rigidity of maternal beliefs and the outcomes considered. Results underline the centrality of supervisor perceived negative behaviors in sustaining working mothers after the long-term leave, when irrational beliefs regarding motherhood threaten their well-being. Practical implications for HR management are discussed.