Abstract Background Inequality in postnatal care (PNC) has remained a challenge in many low- and middle-income countries, like Bangladesh and Pakistan. The study examines within-country and between-country inequality in utilizing PNC services for Bangladesh and Pakistan. Methods The study used the latest Demographic and Health Survey (DHS, 2017–2018) datasets of Bangladesh and Pakistan for women aged 15–49 years who had given at least one live birth in the three years preceding the survey. As outcome variables, three PNC service indicators were considered: PNC check of women, PNC check of newborns, and adequate PNC content of newborns. Concentration curves and equiplots were constructed to visually demonstrate inequality in PNC services. For ordered equity strata with more than two categories, the relative concentration index (RCI), absolute concentration index (ACI), and slope index of inequality (SII) were calculated to measure inequalities in the utilization of PNC services. For two categories equity strata, rate ratio (RR) and rate difference (RD) were calculated. Results In Bangladesh, the level of inequality was high and almost the same for the PNC check of women and newborns based on women’s education (PNC women- RCI: 0.404, ACI: 0.403, SII: 0.624; and PNC newborn- RCI: 0.402, ACI: 0.402, SII: 0.622), wealth (PNC women- RCI: 0.448, ACI: 0.448, SII: 0.643; and PNC newborn- 0.441, ACI: 0.441, SII: 0.633), and number of ANC visits (PNC women- RCI: 0.329, ACI: 0.329, SII: 0.595; and PNC newborn- RCI: 0.329, ACI: 0.329, SII: 0.594). In Pakistan, the level of inequality was higher for the PNC check of women among all PNC services based on women’s education (ACI: 0.388 and SII: 0.676) and wealth (ACI: 0.397 and SII: 0.598). For Bangladesh and Pakistan, RR values (2.114 and 3.873, respectively) indicated greater media exposure-related inequality in adequate PNC content of newborns. Inequality in facility delivery was highest for PNC checks of women and newborns in Bangladesh (PNC women- RD: 0.905, PNC newborn- RD: 0.900) and Pakistan (PNC women- RD: 0.726, PNC newborn-RD: 0.743). Conclusion Inequality was higher in Bangladesh than in Pakistan for PNC checks of women and newborns based on wealth, media exposure, and mode of delivery. For adequate PNC content of newborns, inequality was greater in Pakistan than in Bangladesh. Country-specific customized policies would better minimize the gap between the privileged and underprivileged groups and reduce inequality.