Pressures related to the COVID-19 pandemic have created the need to develop innovative ways to deliver mental health care, especially for urgent needs. After the launch of a pediatric Emergency Department (ED) Virtual Care service, we aimed to evaluate pediatric ED physicians' experiences with the use of ED virtual care for mental health assessments. This mixed-methods study was conducted at a pediatric academic health center in Ontario, Canada. Pediatric ED physicians who conducted ED virtual mental health assessments from May to December 2020 were eligible. Participants completed a 22-question novel survey and were invited to participate in a focus group. Descriptive and thematic analyses were used to analyze the data. Twenty-nine physicians provided mental health services through the ED virtual care platform. Twenty-five physicians (86% response rate) completed the survey and 3 (10%) participated in a focus group. While many agreed that virtual care benefits patients (67%), key barriers identified included time constraints, lack of mental health clinician support, and uncertainty around the pediatric ED physicians' role in these types of assessments. Despite these barriers, physicians recognized the potential benefit of the ED virtual care service for mental health assessments and were largely amenable to improving this process should mental health support be available. While many physicians agreed that there is a potential benefit of the ED virtual care platform for urgent mental health assessments, time constraints and lack of confidence in providing satisfactory virtual mental health care with minimal mental health support limited its acceptability. These findings can inform the future implementation of mental health services using an innovative virtual ED platform.