Background: In each immunization program, the public participation is a key factor. So, we studies determinants of participation in immunization against Coronavirus disease 2019 (COVID-19) in Iran before distribution of vaccine.Methods: This cross-sectional study conducted in February 2021. It had two formats; interview and online. The questionnaire comprised socio-demographic information, past medical history, perceived susceptibility to COVID-19 infection, and tendency for participating in vaccination against COVID-19. Results: Of 2071 participants, 1020 (49.2%) were men, and 1803 (87.1%) were determined to participate in COVID-19 vaccination program. There was a significant association between positive attitude toward vaccination against COVID-19 and the respondent’s socio-economic status (SES), educational level, reporting non-communicable diseases (NCDs) in themselves/ their first-degree families, perceived susceptibility toward getting COVID-19 infection in the following months in themselves/close family members, and being a healthcare worker. Most respondents were determined to participate in the COVID-19 vaccination because they believed vaccination would be effective in preventing mortality and decreased COVID-19 transmission. Conclusions: SES, educational level, positive history of NCDs, perceived susceptibility toward getting COVID-19 infection, and being a healthcare worker had a significant positive association with the respondents’ intention to participate in COVID-19 vaccination program.