Maternal health service utilization decreases maternal morbidity and mortality. However, the existing evidence is inadequate to design effective intervention strategies in Ethiopia. This study aimed to examine the utilization of maternal health service and identify its determinants among women of reproductive age in southern Ethiopia. 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. 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. 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). 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.