Background Immediate postnatal care (PNC) satisfaction is considered as the desired outcome of the health care system and determines the use of subsequent health care services. There is a paucity of evidence on the level of immediate PNC satisfaction in the study setting. Therefore, the aim of this study was to assess the level of immediate PNC satisfaction and associated factors among women who gave birth in Debre Markos town public health institutions, northwest Ethiopia. Methods An institution-based cross-sectional study was conducted from January 1 to February 28, 2021, and a systematic sampling technique was used to select the postnatal women. An interviewer-administered pretested structured tool was used. The level of immediate PNC satisfaction was measured by Jipi’s postnatal satisfaction with the nursing care questionnaire (JPSNQ). The collected data were entered into EpiData version 4.6.0 and exported to SPSS version 23 for management and analysis. Both bivariable and multivariable binary logistic regression analysis were applied. Adjusted odds ratios (AORs) with corresponding 95% confidence intervals (CIs) were calculated and statistical significance was declared at P -value <0.05. Results A total of 389 postnatal mothers participated in this study with a response rate of 98.73%. Immediate PNC satisfaction was 60.90% (95%CI: 56.50–65.60). Postnatal women having multiparity (AOR=7.31, 95%CI: 4.40–12.17), four and more antenatal care (ANC) visits (AOR=1.90, 95%CI: 1.08–3.36), satisfied by delivery care (AOR=2.05, 95%CI: 1.24–3.40), received friendly care (AOR=7.72, 95%CI: 2.42–13.52) and having companion (AOR=2.48, 95%CI: 1.37–4.50) had higher likelihood of immediate PNC satisfaction. Conclusion Women’s satisfaction with immediate PNC was higher than the national achievements of targets for the client satisfaction. Therefore, health-care providers should encourage frequent ANC visits, friendly care, and companionship to increase the level of immediate PNC satisfaction.