Unproctored and teacher-proctored exams have been widely used to prevent cheating at many universities worldwide. However, no empirical studies have directly compared their effectiveness in promoting academic integrity in actual exams. To address this significant gap, in four preregistered field studies, we examined the effectiveness of unproctored and teacher-proctored exam formats in deterring cheating behavior among university students and the role of academic integrity reminders. All four studies used a double-blind, randomized, controlled design. Before taking an exam, students were randomly assigned to take either an unproctored condition or a teacher-proctored exam, with or without receiving an academic integrity reminder. We found that the unproctored exam format is significantly more effective in reducing cheating than the teacher-proctored exam format and adding academic integrity reminders before the exams significantly reduces cheating. These findings demonstrate that incorporating unproctored exams and pre-exam academic integrity reminders into a university's assessment practices may be a useful strategy for reducing academic dishonesty and upholding assessment validity.