Online teaching has gained more momentum since the outbreak of the COVID-19 pandemic. While this mode offers many benefits, one major concern is maintaining academic integrity, as online instruction can provide more opportunities for cheating. This study aimed to explore students' attitudes toward cheating in online assessments (OAs) and any potential differences based on gender and nationality. Since our purpose was to perform a cross-cultural examination of cheating behaviors in an academic environment, we conducted the study in culturally diverse countries. The participants were 629 university students from Iran, Romania, and Lebanon. They completed a questionnaire about academic integrity in OAs. The results showed that 60% of the participants had no negative views on cheating in OAs, 58.5% admitted to cheating in OAs themselves, and 85% viewed OAs as less reliable than in-person assessments. During OAs, the most common ways of cheating included using notes on paper, relying on course materials, and sharing answers through social media and messaging apps. The main motivations for cheating included stress, time constraints, and the desire to achieve a higher grade, while factors that deterred cheating included moral and social stigma and the rights of other students. The study found no significant difference in attitudes toward cheating in OAs between male and female participants, but there were significant differences between students of different nationalities (p < 0.05).