Background: Understanding the mental health needs of healthcare workers during coronavirus disease 2019 (COVID-19) pandemic with a view of mitigating its impact on occupational functioning is vital.Aim: To determine the prevalence and correlates of psychological distress amongst healthcare workers.Setting: The study was carried out in Nigeria during COVID-19 pandemic.Methods: A cross-sectional quantitative study using a convenience sample was conducted amongst healthcare workers. The survey comprised of two Google formatted self-report questionnaires, a 12-item General Health Questionnaire and a questionnaire containing socio-demographic, work related and knowledge of COVID-19 variables. Questionnaires were distributed via closed professional WhatsApp platforms. Data were analysed using descriptive statistics, chi-square test and logistic regression.Results: There were 313 respondents and prevalence of psychological distress was 47.0%. Females were almost twice as likely to have psychological distress as males (OR = 1.92, 95% CI: 1.21–3.04, p = 0.006). Healthcare workers who had no contact with COVID-19 positive patients had an 87% reduced risk of psychological distress (OR = 0.13, 95%CI: 0.23–0.25, p = 0.018) compared with those who had contact with COVID-19 positive patients. Healthcare workers with poor knowledge of COVID-19 had a 44% reduced risk of psychological distress compared with those with good knowledge (OR = 0.56, 95% CI: 0.34–0.93, p = 0.025).Conclusion: Findings revealed that healthcare workers in Nigeria reported psychological distress during COVID-19 pandemic. Greater risk was amongst females and those who had contact with COVID-19 positive patients whilst poor knowledge was protective.