Background/purpose. Self-efficacy plays a crucial role in enhancing performance in complex tasks such as mathematical modeling, yet its impact remains underexplored. This study examines whether there are influences on students' self-efficacy in modeling. Materials/methods. The research method employs a quantitative design, utilizing regression analysis. This study involved all eighth-grade students in Landak Regency, West Kalimantan. The sample consisted of 133 students from three randomly selected schools, which were chosen from 18 A-accredited schools. The research instruments consisted of the Mathematical Modeling Test and the Self-Efficacy Questionnaire. Instrument valid using Aiken's V method, with 0.83 (V[greater than or equal to]0,4). All 133 students have to complete two instruments. Scores from both instruments are classified into low, medium, and high categories. A simple linear regression analysis is utilized to examine the hypothesis: "Is there any impact of the self-efficacy (X) against the ability in mathematics modeling (Y)?". Applying SPSS v.26, the regression prerequisite test was met. Results. The results of relationship between the capabilities of self-efficacy students and the ability students in mathematical modeling (Sig.= 0.000 < 0.05), with a regression equation Y=-22.150+ 1.213X, that shows every 1-point increase in self-efficacy is predicted to increase mathematical modeling ability by 1.213 points, obtained by 26.7% of the variance in students' mathematical modeling ability can be explained by their level of self-efficacy. The results analysis shows that students with high self-efficacy successfully completed all modeling phases, whilst low self-efficacy students demonstrated difficulties in formula application and accurate calculations. Conclusion. These results emphasized the importance of strengthening self-efficacy to enhance mathematical modeling ability.