BACKGROUND: The content of mindfulness-based social-emotional learning (MBSEL) concentrates on conscious attention to thoughts, emotions, and bodily senses, which reduces test stress and anxiety and also leads to an increase in students' performance regarding stress management and improving responsible behaviors. This study aimed to explore the relationship between the degree of test anxiety and the level of students' mindfulness and the academic performance of nursing students. MATERIALS AND METHOD: This descriptive cross-sectional study was conducted during 2021-2022, and the target population included all nursing students of the Faculty of Nursing and Midwifery, Shiraz University of Medical Sciences, Shiraz, Iran. The sample size is determined by Cochran's formula (151 participants). The sampling method was also simple random. The Sarason's test anxiety questionnaire and the short form of the Freiburg Mindfulness Inventory were used to collect data. The student's academic performance was also evaluated based on their previous academic semester scores. Data were analyzed by SPSS version 23 software through descriptive statistics, Pearson correlation coefficient, and an independent t-test. RESULT: According to the Pearson correlation coefficient, there was an inverse and significant correlation between the variable of mindfulness and the level of test anxiety in nursing students (r = -170, P = 0.033), a positive and significant correlation between academic performance and mindfulness (r = 0.284, P = 0.001), and a negative and significant correlation between academic performance and test anxiety level (r = -0.170, P = 0.037). CONCLUSION: Mindfulness-based cognitive therapy is effective in reducing negative thoughts, ineffective attitudes, depression, stress, and anxiety, and this therapy strategy can be used to reduce or treat anxiety and worry in students.