This study aims to determine the influence of thesis supervisor support and academic stress on the timely completion of undergraduate theses among students of the Education Study Program, Faculty of Economics, Universitas Negeri Medan, cohort 2021. Timely thesis completion is one of the indicators of students’ academic success and is influenced by various internal and external factors, including support from thesis supervisors and the level of academic stress experienced by students during the thesis-writing process. Thesis supervisor support plays a role in providing guidance, motivation, and academic assistance, while academic stress may affect students’ ability to complete their final projects optimally. This research employed a quantitative approach using an ex post facto method. The population consisted of all students of the Education Study Program, Faculty of Economics, Universitas Negeri Medan, cohort 2021. The sampling technique used was purposive sampling, with a total of ... student respondents. Data were collected through questionnaires that had been tested for validity and reliability. The data analysis techniques included classical assumption tests, multiple linear regression analysis, t-tests, F-tests, and the coefficient of determination (R²). The results showed that thesis supervisor support had a positive and significant effect on the timely completion of theses. Academic stress had a negative and significant effect on the timely completion of theses. Simultaneously, thesis supervisor support and academic stress significantly influenced the timely completion of theses among students of the Education Study Program, Faculty of Economics, Universitas Negeri Medan, cohort 2021. These findings indicate that the higher the level of support provided by thesis supervisors and the lower the level of academic stress experienced by students, the greater the likelihood that students will complete their theses on time.