Background: Given the significance of consequences of Covid-19, as well as the health of students, this study aimed to predict the fear of Covid-19 based on spiritual well-being and self-efficacy among Iranian students: focus on the mediating role of mindfulness. Methods: This study was a descriptive correlational study. An online sampling method was used, and the sample included 396 students in Tehran. Mindful Attention Awareness Scale (MAAS), General Self-Efficacy Scale (GSE), Fear of Covid-19 scale, and Paloutzian & Ellison's Spiritual Well-being Scale (SWBS) were used for data collection. An independent t-test, Pearson correlation, and regression test were used to analyze the data. Results: The results show that the overall effects of religious well-being (β =-0.192, P=0.001), existential well-being (β = -0.227, P=.001), and self-efficacy (β=-0.093, P=.013) were significant. The indirect effects of religious well-being (β =-0.026, P=0.001), existential well-being (β =-0.013, P=0.016), and self-efficacy (β=-0.04, P=0.001) were significant. The direct effects of religious well-being (β=-0.253,P=0.001), existential well-being (β =-0.205, P=0.016), and self-efficacy (β =-0.133, P=0.013) were significant. Conclusion: This study discovered that spiritual well-being, self-efficacy, and mindfulness are associated with a reduction in perceived fear of Covid 19 in Iranian students and also expanded our knowledge of mediating roles of mindfulness.