Background: Maternal heart disease is a leading cause of maternal morbidity and mortality, and while pregnancy-related cardiac complications have been studied extensively, data on postpartum cardiac events and the influence of obstetric characteristics remain limited, particularly in low- and middle-income countries such as Bangladesh. The purpose of the study was to evaluate obstetric characteristics and the incidence of postpartum cardiac events in women with pre-existing heart disease. Methods: This hospital-based cohort study was conducted at the Department of Obstetrics and Gynaecology, Fetomaternal Medicine Unit, Dhaka Medical College Hospital, the Department of Fetomaternal Medicine, BSMMU, and the Department of Cardiology, NICVD, Dhaka, Bangladesh, from February 2020 to March 2021. Seventy-three postpartum women with pre-existing heart disease were enrolled. Data on demographics, obstetric history, cardiac status, and maternal outcomes were collected and analyzed using SPSS 26; p <0.05 was significant. Results: Among 73 women with pre-existing heart disease, most were 18–30 years old (67.1%) and multiparous (78.1%), with term deliveries (83.6%) and LUCS (75.3%) common. Rheumatic valvular disease predominated (56.2%), followed by congenital heart disease (27.4%) and cardiomyopathy (16.4%), with 93.2% in NYHA I–II. Postpartum cardiac events occurred in 45.2%, higher in incidentally diagnosed women (61.8% vs 30.8%), particularly in multiparous, term, and vaginal deliveries. Conclusion: Women with pre-existing heart disease are at significant risk of postpartum cardiac complications, especially if undiagnosed, multiparous, or delivered vaginally, highlighting the need for early recognition and careful peripartum management.