Objective: To estimate the psychological impact of COVID-19 on university students in Saudi Arabia. Method: The Depression Anxiety Stress Scales 21 (DASS-21) questionnaire was distributed via the university students’ emails. Of the 71,945 full-time undergraduate university students, 3,515 respondents completed the questionnaire. The questionnaire also included demographic information, such as age, gender, source of income, living arrangements, smoking status, and weekly physical exercise. Results: Nearly half of the participants experienced normal levels of stress (40.5%, n=1425) and anxiety (42.4%, n=1492). In terms of depression, nearly one-third were classified as normal (29.3%, n=1031); however, one-fourth were classified as extremely severe (23.8%, n=838). There were significantly higher levels of stress among female students. Additionally, a significantly higher rate of male students (50.4%, n=667) had normal anxiety levels compared to female students (37.7%, n=825). Finally, a significantly higher proportion of female students had symptoms of depression (72.66%, n=1,592) compared with the degrees of depression among male students (67.37%, n=892). Conclusion: We detected that stress, anxiety, and depression increased during the COVID-19 pandemic, and university students were at higher risk of developing mental health issues. An ongoing follow-up and monitoring of psychological consequences and their potential negative impact on academic performance and mental wellbeing are required.