The outbreak of COVID-19 has affected the world with over two million cases globally. Malaysia has witnessed over 5,000 with almost 100 deaths as of 22 April 2020. Knowledge on the incubation period of COVID-19 is scarce due to the novelty of the virus. The aim of this study was to determine the incubation period of COVID-19 infection in the district of Petaling in Malaysia. A cross-sectional study was conducted using secondary data from the Petaling District Health Office. We analysed data of laboratory-confirmed COVID-19 cases notified to the Petaling District Health Office between 3 February 2020 and 13 April 2020. Our study included 219 cases. The median incubation period of COVID-19 among the cases was five days (interquartile range 3.0-8.0). Four main clusters were identified, with significant difference found between two of the clusters. Cluster A has a shorter incubation period 3.5 (3.0-6.8) compared to cluster B as most of the confirmed cases knew the source of infection. COVID-19 incubation period in Petaling, Malaysia fits within the range estimated by the World Health Organization. Based on the upper value of the incubation period interquartile range in our study, the length of quarantine and period of contact tracing should be at least 8 days. This finding is in accordance with our current practice to control the spread of COVID-19