Objectives: To evaluate the association of sleep bruxism activity with smartphone addiction and sleep quality among university students during COVID-19 pandemic. Material and Methods: A cross-sectional online survey with 546 university students in social distancing was conducted (May 29th to June 2nd 2020). Participants should be undergraduate and graduate students enrolled in Brazilian public/private universities. A self-completed questionnaire collected sociodemographic characteristics, academic information, and severity of possible sleep bruxism (PSB) activities (grinding, bracing, and thrusting). Students answered the Brazilian version of Pittsburgh sleep quality index (PSQI-BR) and short form of the smartphone addiction scale (SAS-SV). Descriptive statistics and multinomial logistic regression were performed (p=0.05). Results: Sample mean age was 24.9 (±5.5) years. Students with higher scores of PSQI-BR were more likely to present severe PSB-bracing (OR=1.154; 95%CI=1.057-1.260), severe PSB-grinding (OR=1.133; 95%CI=1.048-1.225) and severe PSB-thrusting (OR=1.197;95%CI=1.107-1.294). Students who had children presented 3 times more chance (OR=3.193; 95%CI=1.236-8.250) to report severe PSB-thrusting. Being female increased the chance of reporting moderate (OR=3.315; 95%CI=1.333-8.914) and severe (OR=2.940; 95%CI=1.116-7.747) PSB-thrusting. Students not enrolled in distance learning presented 2 times more chance (OR=2.638; 95%CI=1.233-5.649) of reporting moderate PSB-grinding. Students with higher scores in SAS-SV had a slight increase in the chance of presenting mild (OR=1.042; 95%CI=1.009-1.077) and moderate (OR=1.065; 95%CI=1.018-1.115) PSB-bracing, as well as mild (OR=1.044; 95%CI=1.011-1.078) and moderate (OR=1.041; 95%CI=1.005-1.077) PSB-thrusting. Conclusion: Smartphone addiction, worse sleep quality, having children, female sex and not being enrolled in distance learning were associated possible sleep bruxism during COVID-19 pandemic.