Background: Academic underperformance in mathematics is widespread across all educational levels. To comprehend its causes, it is crucial to analyze various factors that impact academic advancement in mathematics through their interplay. The present study aimed to develop and validate a mathematics self-efficacy scale for university students. Methods: The research method was correlational and of instrument development type. The statistical population included all undergraduate students of Islamic Azad Universities in Tehran in 2021, of which 300 were selected as a sample using a multi-stage cluster random sampling method. In the process of scale construction, a set of items was initially selected based on a review of the research literature in the field of mathematics self-efficacy and the identification of valid tests in this area. Then, a preliminary version of the questionnaire was administered to a sample of 300 students. Factor analysis, Cronbach’s alpha coefficient, and Pearson correlation coefficient were used to analyze the data. Results: Based on the results of the exploratory factor analysis, the mathematics self-efficacy scale consisted of four components: mathematical achievement and success, general mathematical self-efficacy, mathematical anxiety, and mathematical stress. Cronbach’s alpha for the four components were 0.97, 0.95, 0.95, and 0.93, respectively. The results of the convergent validity evaluation showed that all four components of the mathematics self-efficacy scale were positively correlated with the intrinsic and extrinsic motivation components of the Academic Motivation Scale and negatively correlated with academic motivation. Conclusion: The components of the mathematics self-efficacy scale had acceptable internal consistency and convergent validity. Therefore, it can be concluded that the designed scale can be used as a valid tool to measure the level of mathematics self-efficacy in university students.