Background: COVID-19 was declared a pandemic by the World Health Organization on 11 March 2020. From the beginning of the pandemic, there was no effective pharmaceutical intervention to halt or hold up the spread of this novel disease. Therefore, most countries, including Malaysia, resorted to break the chain of transmission by restricting population mobility through the implementation of the Movement Control Order (MCO). We aim to determine the population mobility trend across the various phases of the MCO during the COVID-19 pandemic in Malaysia by studying the confirmed COVID-19 cases with the Google mobility data. Methodology: The average mobility percentage changes in Retail and Recreation, Grocery and Pharmacy, Parks, Transit Stations, and Workplaces were the components studied in relation to the various MCO phases and daily COVID-19 confirmed cases. The percentage difference was calculated by subtracting the average percentage changes for each MCO phases from the pre-MCO level. Additionally, the percentage difference was also calculated for inter-MCO phases as well. Results: The average mobility percentage changes reduced most drastically during the MCO phases across all the mobility components as compared to the other phases. The average mobility percentage changes in comparison to the pre-MCO levels across Retail and Recreation, Grocery and Pharmacy, Parks, Transit Stations, and Workplaces was −45.8%, −10.6%, −27.7%, −60%, and −34.3%, respectively. In addition, the average mobility percentage changes increased the most during CMCO as compared to MCO. Discussions: Malaysia implemented multiple measures to contain the COVID-19 pandemic since January 2020, culminating in the execution of the MCO. Though doubts on the effectiveness of the MCO were raised at the early stage of its implementation as mass movements persisted, strict enforcement and improved awareness of the impacts of COVID-19 brought significant improvement in compliance, which has been deemed the main reason behind the decrease in new COVID-19 cases since mid-April of 2020. Conclusion: Based on the downtrends of new and active COVID-19 cases, it can be concluded that the MCO has been effective, provided that compliance to the MCO is maintained. This study could serve to a certain degree to governments and policy makers as a tool to consider the relaxation of the lockdown conditions.