Introduction: The study aimed to investigate the associations between skipping breakfast and various health risk behaviours and mental health in university students in 28 countries. Methods: Using a cross-sectional study design, 21,972 university students with a median age of 20 years from 28 countries in Africa, the Americas and Asia, replied to self-reported measures of breakfast consumption, health compromising behaviours, mental health measures and protective factors. Results: In adjusted logistic regression analysis, infrequent and/or frequent breakfast skipping was associated with inadequate fruit and vegetable intake, frequent soft drink intake, not avoiding fat and cholesterol, current binge drinking, current tobacco use, gambling, not always wearing a seatbelt, inadequate physical activity, inadequate tooth brushing, not seeing a dentist in the past year and having been in a physical fight. In addition, infrequent and/or frequent breakfast skipping was associated with depression, lower happiness, posttraumatic stress disorder, loneliness, short sleep, long sleep, sleep problem, restless sleep, sleep problem due to traumatic event, and poor academic performance. Discussion: We found evidence that skipping breakfast was associated with 10 of 15 health risk behaviours, all of nine poor mental health indicators and poor academic performance.