This study aimed to explore the concurrent relationship between core self-evaluation (CSE) and depression, as well as the mechanisms involved in an actor-partner interdependence mediation model (APIMeM). The participants included 1,698 Chinese heterosexual couples (N = 3,396 individuals), with an average age of 42.95 years (SD = 4.5) for males and 41.21 years (SD = 4.1) for females. The study utilized the Core Self-Evaluation Scale, the Center for Epidemiologic Studies Short Depression Scale, and the Relationship Assessment Scale for measurement. The results indicated that higher core self-evaluation was associated with lower depression both directly and indirectly. Specifically, a higher level of core self-evaluation was linked to greater relationship satisfaction, which in turn was associated with lower depression. Additionally, partner core self-evaluation influenced depression indirectly in two ways related to gender roles. Notably, for married females, their partner's relationship satisfaction was negatively related to their depression. In conclusion, relationship satisfaction mediates both the actor and partner effects of CSE on depression for couples. This study enriches the theoretical framework regarding the relationship between CSE and depression and suggests implications for mental health interventions targeting couples. Future research should consider diverse cultural backgrounds and incorporate various demographic factors to enhance the generalization of the findings.