Introduction: The COVID-19 pandemic had a negative impact on mental health in the general population. The fear, stress, and uncertainty surrounding that traumatic period could have contributed to the aggravation or possible new onset of obsessive–compulsive symptoms. Methods: The COvid Mental hEalth Trial (COMET) is a nationwide project organized by the University of Campania “Luigi Vanvitelli”, designed as an observational investigation that aimed to gather data from a representative sample of the Italian general population. The current study is a report from the main project and it focuses on obsessive–compulsive (OC) symptoms. Results: A total sample of N = 20,720 took part in the survey. N = 2332 individuals had a total Obsessive–Compulsive Inventory—Revised (OCI-R) score greater than or equal to 21 (11.3% of the entire sample), indicating the presence of clinically relevant obsessive–compulsive symptoms. By excluding patients with a history of previous mental illnesses, we still obtained a high number of individuals with an OCI-R score greater than or equal to 21 (N = 2024), representing 10.3% of the overall sample, possibly indicating a new incidence of OC symptoms during the pandemic. Discussion: Our study highlights a substantial new incidence of obsessive–compulsive symptoms in the general public. Risk factors or red flags such as being male, being of working age, living in a highly stressful environment such as one of the Italian regions most affected and severely hit by the pandemic, having higher levels of loneliness, and using substances to cope with stress, should be paid particular attention in order to prevent the development of OC symptoms during a critical and traumatic event such as the COVID-19 pandemic.