This study aimed to examine the relationship between domestic violence, past depressive disorder, unplanned pregnancy, suicide risk, and postpartum depression among Korean women using a mediation model approach. A web-based, cross-sectional survey was performed from September 21 to September 30, 2022. Participants included 1,486 women in their first year postpartum from Chungnam Province, South Korea. The generalized linear model mediation was analyzed using the R-based Jamovi 2.3.21 version program. Of all participants, 8.7% had domestic violence experience, 7.5% had been diagnosed with depressive disorder by the doctor in the past, 33.0% had reported that the last pregnancy was unplanned, 39.9% had postpartum depression, and 11.2% of the participants had a suicide risk. Among the participants with a high risk of suicide, 34.4%, 37.5%, 53.1%, and 96.9% reported experiencing domestic violence, past depressive disorder, an unplanned pregnancy, and postpartum depression, respectively. Postpartum depression partially mediated the relationship between domestic violence, past depressive disorder, and suicide risk and completely mediated the relationship between unplanned pregnancy and suicide risk. Our findings highlight the necessity for screening and early intervention for suicide risk and postpartum depression from pregnancy to the first year postpartum.