Globally, 53% of women in reproductive age group use modern methods of contraception, with less than one percent of which using implants. In Ethiopia and other parts of sub-Saharan Africa, short-term contraceptive methods have been more utilized than long-acting methods like implants. Despite their effectiveness, implants have been underutilized due to various reasons. There is a dearth of stronger evidences on those factors in the country in general and the study area in particular. Therefore, this study aimed to identify determinants of implant utilization among married women of reproductive age at Chencha town, Gamo Gofa Zone, Southern Nations, Nationalities, and Peoples' Region (SNNPR) of Ethiopia. A community-based case-control study design was conducted among 324 women of reproductive age, 90 cases (users of implants) and 234 controls (users of short-acting contraceptives) from July to August 2017. Data were collected using a pretested, structured questionnaire through face-to-face interview. The data were entered and coded using Epi info 3.5.1 and then exported to Statistical Package for Social Sciences (SPSS) version 20 for cleaning and analysis. Descriptive analysis was done to quantify proportions, means, and standard deviations of variables. Bivariate and multivariable logistic regressions were done to identify the determinants of implant utilization. A total of 324 married women of reproductive age group were interviewed with response rate of 98%. In this study, the major determinants for implant utilization were desire to have 3–4 children {AOR = 0.104, 95% CI (0.03, 0.4)}, husband disproval {AOR = 0.11, 95% CI (0.038, 0.314)}, joint decision {AOR = 3.11, 95% CI (1.02, 9.48)}, and decision by other persons {AOR = 0.065, 95% CI (0.012, 0.352)}. This study found out that desire to have more children, husband disapproval, joint decision making, and decision by other persons were determinants of implant utilization among the target women. Implant utilization would improve through strengthening existing interventions targeting women with high fertility desire, transformation of gender norms in household decisions, and counseling for informed decisions.