Background: Recent evidence showed substantial negative mental health outcomes associated with the current COVID-19 pandemic, including trauma-related symptoms although the effects on the Italian population who were subjected to unprecedented nationwide lockdown measure remains unknown. The Global Psychotrauma Screen (GPS) is a brief instrument designed to assess a broad range of trauma-related symptoms with no available validation in the Italian population. Aims: This study aimed at examining the factor structure of the Italian version of the GPS in a general population sample exposed to the COVID-19 pandemic and at evaluating trauma-related symptoms in the Italian population in the context of specific COVID-19 related risk factors associated with the implementation of lockdown measures and social distancing. Methods: Cross-sectional web-based observational study, as part of a long-term monitoring programme of mental health outcomes in the general population. 18147 participants completed a self-report online questionnaire to collect key demographic data and to evaluate trauma-related symptoms using the GPS, PHQ-9, GAD-7, ISI and PSS. Validation analyses included both exploratory and confirmatory factor analysis, and correlation analyses. Results: Exploratory factor analyses supported both a two-factor and a three-factor model. Confirmatory factor analysis showed that a one-factor solution that was used as a baseline comparison showed acceptable fit indices, the two-factor solution showed good fit indices, but the best fitting model was a three-factor solution, with Negative Affect (symptoms of depressed mood, anxiety HP, irritability HP), core Post-traumatic Stress Symptoms (PTSS) (avoidance, re-experiencing, hyperarousal and insomnia HP) and Dissociative symptoms. GPS Risk factors as well as specific COVID-19 related stressful events, were associated with GPS total as well as the three factor scores. Conclusions: Our data suggest that a wide range of trauma-spectrum symptoms were reported by a large Italian sample during the COVID-19 pandemic. The GPS symptoms clustered best in three factors: Negative Affect symptoms, Core PTSS, and Dissociative symptoms. In particular high rates of core PTSS and negative affect symptoms were associated with the COVID-19 pandemic in Italy and should be routinely assessed in clinical practice.