Background. Maintaining good mental health among Emergency Department healthcare workers (ED HCW) is paramount to well-functioning healthcare. We measured mental health and COVID-19 symptoms in ED HCW at a COVID-19 epicenter. Methods. A cross-sectional, convenience sample of adult (>18 years) ED HCW in Brooklyn, New York, USA, who were employed at >50% of a full-time effort, was surveyed September–December, 2020 with reference period March-May 2020. An anonymous email-distributed survey assessed gender, age, race, healthcare worker status (clinical versus non-clinical), SARS-CoV-2 testing, number of people to talk to, COVID-19-related home problems, mental health care interruption during COVID-19, loneliness, and survey date. Outcomes included symptoms of depression, psychological distress, perceived stress, post-traumatic stress disorder (PTSD), anxiety, and resilience measured using validated scales. Results. Of 774 HCW, 247 (31.9%) responded (mean age 38.2±10.8 years; 59.4% White; 52.5% men; 80.1% clinical; 61.6% SARS-CoV-2 tested). Average mental health scores were significantly higher among clinical vs non-clinical HCW (P’s<0.0001-0.019). The proportion reporting a clinically-relevant psychological distress symptom burden was higher among clinical vs non-clinical HCW (35.8% vs 13.8%, p=0.019); and suggested for depression (53.9% clinical vs 35.7% non-clinical, p=0.072); perceived stress (63.6% clinical vs 44.8% non-clinical, p=0.053); and PTSD (18.2% clinical vs 3.6% non-clinical, p=0.064). Compared to non-clinical staff, Medical Doctors and Doctors of Osteopathy reported 4.8-fold higher multivariable-adjusted odds of clinically-relevant perceived stress (95%CI 1.8-12.9, p=0.002); Emergency Medical Technicians reported 15.5-fold higher multivariable-adjusted odds of clinically-relevant PTSD (95%CI 1.6-150.4, p=0.018). Increasing age, number of COVID-19-related home problems and people to talk to, loneliness and mental health care interruption were adversely associated with mental health; being male and SARS-CoV-2 testing were beneficial. Conclusions. COVID-19-related mental health burden was high among ED HCW in Brooklyn. Mental health support services are essential for ED HCW.