Background Burnout has been prevalent among healthcare workers (HCWs). However, the effect of the Coronavirus Disease (COVID-19) pandemic on this phenomenon in HCWs is unclear. Objective This systematic review aims to evaluate the impact of COVID-19 on burnout of HCWs using Maslach Burnout Inventory (MBI). Methods A systematic search was performed on PubMed database for articles published between 1 December 2019 and 30 June 2021. Search strategy combined terms for HCWs, COVID-19, burnout, and MBI. The main outcome of interest was burnout, including both mean prevalence and MBI scores for high emotional exhaustion (EE), high depersonalisation (DP) and low personal accomplishment (PA). Results Four cohort studies, 90 cross-sectional studies and one randomised-controlled trial were included for review. Only one cohort study compared burnout data among HCWs before and during COVID-19. It reported a statistically significant increase in mean EE and PA scores from 21.9 to 24.8 ( p = .001), and 42.7 to 48.7 ( p = .001), respectively. The remaining studies only evaluated burnout data during COVID-19 but were missing burnout data prior to the pandemic for comparison. Across these studies, the overall mean prevalence of burnout among HCWs was 39.95%, with mean MBI EE scores of 22.07, DP scores of 7.83, and PA scores of 32.53. Burnout outcomes were generally comparable across specific healthcare professions such as doctors and nurses. Conclusion Whilst quality research elucidating the effect of pandemic on burnout is lacking, current burnout prevalence among HCWs during COVID-19 is notable.