Objective: There has been concern regarding the mental health impact of coronavirus disease 2019 (COVID-19), and subsequent public health interventions due to isolation, anxiety around the pandemic, and increased conflict in the home. The purpose of this study was to explore current rates of mental health problems, COVID-19 related stress, substance use, and violence at home among adolescents with comparisons across genders. Method: Participants (N = 809) from Canada were recruited via social media to complete an online survey. Participants (Mage = 15.67, SD = 1.37) identified as female (56.2%), male (38.7%), or trans/non-binary individuals (TNBI; 5.1%). Results: A large portion of adolescents met clinical cut-off for depression (51.2%), anxiety (40%) and Post-Traumatic Stress Disorder (45%). High rates of ADHD, ODD, and social phobia symptoms (ranging from 9%-20%) were also reported. Adolescents were mainly concerned with the health of family members and vulnerable populations, as well as the increased family stress at home during COVID-19. Rates of substance use were higher than expected with over 50% of youth engaging in some form of substance use, and almost 20% engaging in regular substance use. Rates of experiencing and perpetrating psychological violence at home were higher than physical violence and were close to rates in high-risk populations. TNBI and females reported higher rates of mental health problems, and violence at home compared to males. Conclusions: Increased rates of mental health problems, substance use, and violence in the home necessitate targeted supports that encourage positive coping amidst the additional stresses of COVID-19.