It is part of the second phase of the project and the under construction line stretches from Madhavaram Milk Colony to Sholinganallur.

[5] In July 2016, Government of Tamil Nadu announced that the second phase would have three lines totaling 104 km (65 mi) in length with 104 stations.

[8][16][17] On 14 February 2021, Prime Minister of India announced that the government has set aside ₹63,000 crore (US$7.3 billion) for the construction of phase II and further extension.

[19] In 2022, the state government proposed a branch extension for the fifth line from Koyambedu to Avadi, covering an approximate 16.1 km (10.0 mi).

[20] In early 2024, feasibility report was submitted by CMRL for the proposed expansion of the line, green lighting the same.