Construction of the first stretch began in June 2009, which spanned the seven stations Koyambedu to Alandur over a distance of and began operation on 29 June 2015. As of February 2021, Chennai Central to St. Thomas Mount on the Green line and Wimco Nagar to Chennai International Airport on Blue line are commercially operational which brings the total operational network to making it the third largest operating metro system in India, after the Delhi metro () and Hyderabad metro ().