Objectives: First responders including firefighters, emergency medical technicians (EMT), paramedics, and police officers are working on the front lines to fight the COVID-19 pandemic and facing a higher risk of infection. This study assessed the seroprevalence among first responders in northeastern Ohio during May- September 2020. Methods: A survey and IgG antibody test against SARS-CoV-2 were offered to University Hospitals Health System affiliated first responder departments. Results: A total of 3080 first responders with diverse job assignments from more than 400 fire and police departments participated in the study. Among them, 73 (2.4%) were seropositive while only 0.8% had previously positive RT-PCR results. Asymptomatic infection accounts for 46.6% of seropositivity. By occupation, seropositive rates were highest among administration/support staff (3.8%), followed by paramedics (3.0%), EMTs (2.6%), firefighters (2.2%), and police officers (0.8%). Seroprevalence was not associated with self-reported exposure as work exposure rates were: paramedics 48.2%, firefighters 37.1%, EMTs 32.3%, police officers 7.7%, and administration/support staff 4.4%. Self-reported community exposure was strongly correlated with self-reported work exposure rate rather than seroprevalence suggesting a potential impact of risk awareness. Additionally, no significant difference was found among gender or age groups; however, black Americans have a higher positivity rate than other races although they reported lower exposure. Conclusions: Despite the high work-associated exposure rate to SARS-CoV-2 infection, first responders with different roles demonstrated seroprevalence no higher than their administrative/supportive colleagues, which suggests infection control measures are effective in preventing work-related infection.