Background: The purpose of this study is to evaluate the knowledge, attitudes, and behaviours (KAB) of health and non-health-related students at university concerning oral health. Materials and Methods: This cross-sectional study with a 3-month duration in 2023 was conducted amongst King Khalid University (KKU) students. This study used a self-administered, anonymous web-based survey with a simple random sampling strategy as part of its cross-sectional design. The questionnaire had four sections totalling 26 questions to evaluate KAB. A chi-square test was used to evaluate significant differences between categories. Results: Of the 845 respondents who completed the survey, 43.78% were health-related students, while 56.21% were non-health-related students. The completed responses included bacteria causing gingival problems (60.81% vs. 36%), fizzy soft drinks adversely affecting teeth (67.83% vs. 40%), tobacco chewing or smoking possibly causing oral cancer (68.37% vs. 44%), white patches or dental plaque on teeth (61.89% vs. 41.47%), brushing teeth twice a day to improve oral health (81.62% vs. 42.52%), keeping teeth clean (64.86% vs. 41.68%), improper brushing leading to gum disease (70% vs. 40.63%), brushing with fluoridated toothpaste to prevent tooth decay (63% vs. 40%), bleeding gums denoting gum infection (26.98% vs. 21.30%), the importance of teeth similar to any body part (61.62% vs. 37.89%), prioritising teeth as other parts of the body (61.05% vs. 36.21%), brushing teeth twice daily (55.67% vs. 37.05%), and routine dental check-ups (55.40% vs. 14.10%) for health and non-health-related students, respectively (p < 0.05). Conclusion: The results of the current study demonstrated less oral health KAB in non-health-related students than in health-related students. Nonetheless, healthcare students provided erroneous information regarding oral health. Therefore, we urge the appropriate authorities to offer health and non-health-related students the best oral health promotion programmes and services, thereby seeking to improve their oral health knowledge while stressing the importance of practising excellent oral hygiene.