University students are a vulnerable group for poor dietary intake, insufficient physical activity and sedentary behaviour. The purpose of this study was to examine the impact of coronavirus disease (COVID-19) on university students' dietary intake, physical activity, and sedentary behaviour. Participants were students ( = 125) from the Universities of Saskatchewan and Regina. An online questionnaire was administered retrospectively (for prepandemic) and prospectively (during the pandemic) to examine students' dietary intake, physical activity, and sedentary behaviour. Overall, nutrient and caloric intakes were significantly reduced ( < 0.05) during the pandemic, and alcohol intake increased ( = 0.03). Before the pandemic, 16% and 54% of the participants were meeting the Canadian 24-Hour Movement Guidelines for Adults (18-64 years) of 150 min of moderate-vigorous physical activity and 8 h or less of sedentary activity, respectively. Only 10% met the guidelines for physical activity while 30% met the guidelines for sedentary behaviour during the pandemic. The minutes per week spent engaging in moderate to vigorous physical activity during the pandemic decreased by approximately 20% ( < 0.001). The hours spent in sedentary activities increased by 3 h per day ( < 0.001). Our findings confirm that during the pandemic, students' inadequate dietary intake, high alcohol consumption, low physical activity, and high sedentary behaviour were significantly compounded. During COVID-19, the nutrient and caloric intakes of university students decreased, and alcohol intake increased significantly. University students' physical activity levels decreased, and sedentary activity increased significantly during COVID-19. During COVID-19 students did not engage in sufficient physical activity to offset the increased sedentary behaviour.