Data from the United Arab Emirates about the mental health status of the younger population is limited. The current study aimed to assess the prevalence of anxiety, depression, and risk for PTSD among school students post lockdown of the current COVID-19 pandemic. A sample of 3745 students and their parents across the country answered a web-based survey. Parents provided bio-demographic data and students answered questions from the Mood and Feeling Questionnaire (MFQ-Child Self-report), Screen for Child Anxiety Related Disorders (SCARED-Child Version), and Children’s Revised Impact of Event Scale (CRIES-8). Findings showed that the risk for PTSD was the most prevalent (40.6%), followed by symptoms of anxiety (23.3%), and depression (17.1%). For gender differences, symptoms of the three conditions were higher in female students by 6.9%. Moreover, symptoms of depression and anxiety were found to be higher among late adolescents. Further analysis revealed that having medical problems (β = 2.0, p < 0.001) and witnessing the death of a close family member due to COVID-19 (β = 1.7, p < 0.001) were positive predictors associated with PTDS, depression, and anxiety. The study concluded that post COVID-19 lockdown, symptoms of anxiety, depression, and risk for PTSD are prevalent among students in the UAE. Researchers recommend the initiation of a national school mental health screening program and the provision of follow-up services for vulnerable students. Another must-have is the integration of a mental health support system in the emergency and disaster preparedness future plans.