Background This study investigated the prevalence of obesity among university students in Saudi Arabia’s western region, as well as its association with gender, smoking, consumption of sugary drinks, and hours of sleep. Methods A cross-sectional study recruited a simple random sample of students from King Abdulaziz University (KAU) in Saudi Arabia’s western region. In this study, the Arab Teens Lifestyle (ATLS) questionnaire was used. The survey was conducted between April and June 2022. Results In total, 659 students participated (313 males [37.3%] and 437 females [66.2%]). One-fourth of the students, 158 (24%), were overweight, and 83 (12.7%) were obese. Male participants were overweight or obese by a rate of 32.6% and 19.4%, respectively. Female overweight and obese rates were 16.2% and 6.6%, respectively. Moreover, obesity/overweight rates were 43.6% in the urban area and 36.9% in the rural area (P=0.03). A total of 370 participants (56.14%) slept less than 8 hours per day, 185 (28.1%) spent more than five hours per day watching television or using the internet, and 303 (46%) ate breakfast on a regular basis. Obesity/overweight was more common in smokers than in nonsmokers (59.7% vs 32.8%, P=0.01). The prevalence of obesity was lower among those who walked three days or more per week (28.1% vs 44.1%; P=0.01) and ran/jogged outside or on a treadmill three days or more per week (29.5% vs 39.8%; P=0.03) than among those who ran/jogged less than three days per week. Student obesity was independently predicted by being male (P=0.01), drinking more sugary drinks (P=0.01), smoking (P=0.03), and sleeping for fewer hours (P=0.03). Conclusion Obesity was more prevalent in male students, with a prevalence of 24%. Male gender, consumption of more sugary beverages, smoking, and sleeping for fewer hours were all independent predictors of obesity among university students.