Objective: This study was conducted to determine the relationship between nursing students' clinical performance self-efficacy with their academic self-efficacy and academic achievement. Material and Methods: The research was applied in a descriptive and correlational design. The research was carried out in Istanbul between January and March 2021. The population of the study consisted of 1046 students studying in the Nursing Department of the Health Sciences Faculty of Marmara University. The sample size was calculated with the G-power program and the sample size was found to be 243. The study was completed with 307 students. Information Form, Clinical Performance Self- Efficacy Scale, and Academic Self-Efficacy Scale were used to collect data. Academic achievement was evaluated by the overall academic grade point average. In addition to descriptive statistics, Mann-Whitney U test, Kruskal-Wallis H test, and Spearman Correlation test were used to evaluate the data. Results: It was determined that the general academic grade point average of the students was 3.06 [standard deviation (SD)=0.48], the Academic Self-Efficacy Scale mean score was 19.43 (SD=4.43) and the Clinical Performance Self-Efficacy Scale mean score was 66.56 (SD=17.52). It was found that there was a low level positive correlation between the students' general academic grade point and Clinical Performance Self-Efficacy Scale mean scores (p=0.000); a moderate correlation was found between the Academic Self-Efficacy Scale and Clinical Performance Self-Efficacy Scale mean scores (p=0.000). Conclusion: It was determined that the students' academic self-efficacy and clinical performance self-efficacy were moderate, and there was a positive relationship between academic achievement and academic selfefficacy and clinical performance self-efficacy.