Background: University life is a crucial period when dietary habits and lifestyle behaviours are formed and may have long-lasting effects on the development of obesity and related chronic diseases. Aim: To investigate the association of overweight/obesity with dietary habits, physical activity, screen time and sleep duration among university students. Methods: A total of 438 students aged 18–26 years were recruited from Mohammed V University in Rabat, Morocco. Anthropometric measurements were assessed using standardized equipment. Data regarding dietary habits, physical and sedentary activities were collected via a self-administered questionnaire. Results: The prevalence of overweight and obesity was 14.8% and 1.6%, respectively. Students who reported frequent consumption (>3 times/week) of fast food, fried potatoes and sugary drinks were more likely to be overweight/obese than peers who did not. Similarly, odds of being overweight/obese were slightly higher among females who reported non-daily intake of fruits and milk or dairy products and among males who ate vegetables less frequently (<7 times/week). Approximately 26% of students were physically inactive, with a higher proportion of females (35.8%) than males (10.7%). Both short and long sleep durations were associated with an increased risk of overweight/obesity in males. In contrast, physical inactivity and increased screen time were associated with a slightly reduced risk of overweight/obesity, particularly in females. Conclusions: Overall, unhealthy dietary habits were associated with an increased risk of overweight/obesity. A similar trend was also observed between abnormal sleep duration and overweight/obesity in males. Interventions to promote healthy dietary and lifestyle habits and prevent overweight/obesity in this population are needed.