Background: Maternal health service utilization decreases maternal morbidity and mortality. However, the existing evidence is inadequate to design effective intervention strategies in Ethiopia. Objectives: This study aimed to examine the utilization of maternal health service and identify its determinants among women of reproductive age in southern Ethiopia. Design: A community-based cross-sectional study was conducted from October 21 to November 11, 2022 on a sample of 1140 women selected randomly from the Northern Zone of the Sidama region. Methods: Data were collected using the Open Data Kit mobile application and exported to Stata version 15 for analysis. We used a multilevel mixed-effects modified Poisson regression with robust standard error to identify determinants of maternal health service utilization. Results: Utilization of antenatal care, health facility delivery, and postnatal care was 52.0% (95% confidence interval: 49.0%, 55.0%), 48.5% (95% confidence interval: 45.6%, 51.4%), and 26.0% (95% confidence interval: 23.0%, 29.0%), respectively. Antenatal care use was associated with receiving model family training (adjusted prevalence ratio: 1.19; 95% confidence interval: 1.06, 1.35), knowledge of antenatal care (adjusted prevalence ratio: 1.54; 95% confidence interval: 1.31, 1.81), perceived quality of antenatal care (adjusted prevalence ratio: 1.02; 95% confidence interval: 1.01, 1.03), and having birth preparedness plan (adjusted prevalence ratio: 1.13; 95% confidence interval: 1.02, 1.25). The identified determinants of health facility delivery use were middle wealth rank (adjusted prevalence ratio: 1.35; 95% confidence interval: 1.03, 1.77), perceived quality of health facility delivery (adjusted prevalence ratio: 1.02; 95% confidence interval: 1.01, 1.03), antenatal care (adjusted prevalence ratio: 1.76; 95% confidence interval: 1.36, 2.26), and high community-level women literacy (adjusted prevalence ratio: 1.55; 95% confidence interval: 1.10, 2.19). Postnatal care use was associated with facing health problems during postpartum period (adjusted prevalence ratio: 1.79; 95% confidence interval: 1.18, 2.72), urban residence (adjusted prevalence ratio: 3.52; 95% confidence interval: 2.15, 5.78), knowledge of postnatal care (adjusted prevalence ratio: 1.11; 95% confidence interval: 1.04, 1.19), and low community-level poverty (adjusted prevalence ratio: 0.43; 95% confidence interval: 0.25, 0.73). Conclusion: Maternal health service use was low in the study area and was influenced by individual- and community-level determinants. Any intervention strategies must consider multi-sectorial collaboration to address determinants at different levels. The programs should focus on the provision of model family training, the needs of women who have a poor perception, and knowledge of maternal health service at the individual level.