It currently consists of two distinctly operational sections from Salt Lake Sector-V to Sealdah, and Esplanade to Howrah Maidan by going underneath the Hooghly River.

It is expected to derive a very high ridership, since it will connect India's two largest commuter railway and long-distance railway terminals, Howrah and Sealdah, along with two of its largest business districts, BBD Bagh and Salt Lake Sector V. At present, more than 100,000 passengers commute through the line every day, and this figure is expected to go up to 1 million after it gets fully completed by 2035.

In January 2004, the Vadodara-based Pacific Consultant International Group conducted a feasibility study for the line.

A new organisation called the Kolkata Metro Rail Corporation Limited (KMRCL) was formed, which would be executing the operations of this line, by commencing construction in 2009.

Due to major setbacks, such as land acquisition, slum relocation, and route alignment problems, the project got delayed.

Just before the tunnel enters the underwater segment, lies a ventilation shaft on the Kolkata bank of Hooghly River, which is the deepest of its kind in India, at 44 metres (144 ft) below ground level.

[36] On 6 March 2024, the truncated route between Esplanade and Howrah Maidan was inaugurated by Prime Minister Narendra Modi.

Out of the 6 underground stations, 3 have been built by ITD Cementation, a part of the Italian-Thai Development Public Company, and the other 3 by Afcons Infrastructure, including the 520 meters underwater stretch.

[40] TVS provides a means to control smoke flow and ensure safe evacuation of passengers in case of a fire, as well as maintain an acceptable environment in the tunnel and station track ways.

The PSDs are a system of full height/half height motorized sliding doors that provide controlled access to the trains and protect the platform edges.

[42] The Construcciones y Auxiliar de Ferrocarriles (CAF), in collaboration with Melco, was to supply 14 trains for this line.

However, the tender was cancelled by the Kolkata Metro Rail Corporation (KMRC) due to technical reasons,[44] and excessive delay in project.

The Bharat Earth Movers Limited (BEML) emerged as the only bidder in the fourth round of bidding for providing the rolling stock.

Another 10 km (6.2 mi) East-West Metro extension project from Howrah Maidan to Santragachi bus terminus has also been proposed.

Rail India Technical and Economic Service (RITES), and the implementing agency for this project was planned to start work on the corridor early in 2017.