Orange Line is a rapid transit metro line of the Kolkata Metro in Kolkata, West Bengal, India. It will connect New Garia with Netaji Subhas Chandra Bose International Airport via two major satellite towns of Kolkata metropolitan region, Salt Lake and New Town. It currently operates between Kavi Subhash and Beliaghata. This line will be one of the most important stretches of Kolkata Metro because it will connect the southern and the eastern parts of the city with Kolkata Airport. The total distance of this route will be 29.87 km (18.56 mi). It has an interchange with Blue Line at Kavi Subhash and will eventually connect with Green Line near IT Centre and Yellow Line at Jai Hind. This line has 5.92 lakh passengers in the 2024-2025 fiscal year.

This project was sanctioned in the budget of 2010–11 by Mamata Banerjee with a project deadline of six years. The execution of this project has been entrusted to the Rail Vikas Nigam Limited (RVNL) at a cost of ₹3,951.98 crore (US$846.75 million). It will help to reduce travel time between the southern fringes of Kolkata to Netaji Subhas Chandra Bose International Airport and will have 23 elevated stations, 1 underground station and 1 at-grade. The terminal Airport station being the underground one.

Work for construction of the terminal station at New Garia for the 29.87 km (18.56 mi) Kavi Subhash-Biman Bandar (via Rajarhat) metro project finally resumed on 14 February 2017 RVNL demarcating the plot they require for the purpose.

The work has been delayed for years due to multiple issues. At first, the Airports Authority of India (AAI) objected the station above the ground, stating that this could be a threat for air traffic. Many underground utilities, power sub-station and water treatment plant had to be shifted. Encroachments and Land acquisition problems held up the project for multiple times.

The 5 km (3.1 mi) stretch from New Garia to Ruby Hospital was expected to start from 2018. As of 2023, the station and associated metro viaduct connections were fully completed with trial runs being conducted over this and other phase 1 stations. RVNL planned to launch the metro over this truncated route before that year's Durga Puja, but this was postponed due to signalling issues.

After lot of hardships and developmental work, the Kavi Subhash–Hemanta Mukhopadhyay section of Orange Line was inaugurated on 6 March 2024 by the Prime Minister Narendra Modi, along with the truncated sections of Taratala–Majerhat under Purple Line and Esplanade–Howrah Maidan under Green Line. A week later after inauguration and a day after commercial run started on Kavi Subhash-Hemanta Mukhopadhyay section, RVNL announced the completion of a 76 m (249 ft) viaduct gap after construction of a single-span open-web girder steel bridge over Tagore Park culvert. This completed the viaduct up to Beliaghata metro station. Trial runs have started over Hemanta Mukhopadhyay-Beleghata metro station and the plan was to open this stretch by the end of 2024. RVNL has faced enormous challenges while working, in one such incident it incurred enormous loss of over 5 crore rupees due to lack of clearance of traffic from Kolkata Police and work being stalled for over 60 days. The Hemanta Mukhopadhyay–Beleghata Orange Line extension was opened on 22 August 2025, along with the truncated sections of Noapara–Jai Hind under Yellow Line and Esplanade–Sealdah under Green Line.

Commercial Operations between Beleghata and Kavi Subhash began on 25 August 2025.

The service starts from 8 am and ends at 8:05 pm, with 60 pairs of services from Monday to Friday. All the trains run at a frequency of 25 minutes.