This multicenter study aims to explore the connections between psychological capital, parenting concerns, and parenting competence in breast cancer patients, while also validating the mediating role of parenting competence between psychological capital and parenting concerns. Employing a cross-sectional study design, we administered a general information questionnaire along with the Parenting Concern Scale (PCQ), Psychological Capital Scale (PSOC), and Parenting Competence Scale (PCS-24) between October 2023 and March 2024 to 223 breast cancer patients across three public hospitals in Hubei Province and Henan Province. Our findings indicate that parenting concerns among breast cancer patients are associated with both patient age (r = -0.189, P = 0.005) and the age of the youngest minor child (r = -0.222, P = 0.001). Moreover, parenting concerns are negatively correlated with parenting competence (r = -0.503, P < 0.01) and psychological capital (r = -0.540, P < 0.01), while parenting competence shows a positive correlation with psychological capital (r = 0.450, P < 0.01). Additionally, psychological capital serves as a mediator in the relationship between parenting concerns and parenting competence. Our study suggests that parenting competence partially mediates the relationship between psychological capital and parenting concerns. Effective interventions should focus on providing psychological and practical resources to patients, addressing the challenges faced by breast cancer families raising minor children, and enhancing social support networks to collectively tackle the psychological issues associated with parenting concerns.