[1] Operated by Metro Trains Melbourne, it is the city's second longest metropolitan railway line at 44 kilometres (27 mi).

[5][6] Significant growth has occurred since its reopening, with proposals to extend the line two stations to Clyde receiving support amongst other works on the corridor.

A $1 billion upgrade of the corridor between Dandenong and Cranbourne is currently under construction, with improvements including the removal of all level crossings, rebuilding stations, and the duplication of 8 km (5 mi) of track.

[11] The line was progressively extended to Koo Wee Rup, Nyora, and Loch in 1890, Korumburra and Leongatha in 1891, and Welshpool, Alberton, and Port Albert in 1892.

[18] In 2008, a package of works were unveiled to upgrade the Cranbourne line to improve frequencies and the quality of service.

[19] In addition to the new siding, the $37 million project also brought a major upgrade to Cranbourne station, which included the construction of an enclosed waiting room, new platform shelters, new toilet facilities, formalised paved pedestrian access, an upgraded bus interchange, and increased security.

[23] In September 2019, Qube Holdings commenced operating a daily service on a short section of the line, hauling containerised cement to the Kimberly-Clark siding at Dandenong South.

[28] Services on the South Gippsland line were fully suspended in 1981 due to limited passenger numbers on the route.

[30] The Bracks governments Victorian Transport Plan, released in 2008, listed the extensions and associated works as a "medium term" project, which was estimated to cost $200 million.

[31] Despite the political promise to revive the railway line for freight and passenger services by the Bracks-led Labor government in 1999, the project was abandoned in 2008 by his successor John Brumby.

[32] In 2013, as part of Public Transport Victoria's Network Development Plan for metropolitan rail, an extension of the Cranbourne line to Clyde was earmarked to begin in the "long-term", which would equate to at least over the next 20 years.

In the lead up to the 2018 state election, the incumbent Andrews government announced the Cranbourne Line Upgrade, a project involving the duplication of 8 km of track between Dandenong and Cranbourne, a rebuilt Merinda Park station, the construction of a new rail connection for the Port Rail Shuttle Network, and the removal of all remaining level crossings on the corridor.

[34] Opposition leader Matthew Guy instead promised that he would extend the Cranbourne line to Clyde if he won the election.

[35] Again in the lead up to the 2022 state election, the City of Casey increased its campaign for the extension of the rail line to Clyde, including the construction of 3 new stations.

[36] The incumbent Andrews government made no commitments to the Clyde rail extension, instead continuing construction on the Cranbourne Line Upgrade.

[37] The 2022 state election resulted in another Labor victory, with the Andrews government pushing ahead with the Cranbourne Line Upgrade, with the extension to Clyde remaining stagnant ever since.

[43] Announced in the lead up to the 2018 Victorian state election, the Cranbourne line would receive a $1 billion upgrade to coincide with the opening of the Metro Tunnel.

[24] Train services on the Cranbourne line are also subjected to maintenance and renewal works, usually on selected Fridays and Saturdays.

The government-owned Public Transport Corporation and later Bayside Trains operated the line for a short 4 years till the 1999 privatisation of Melbourne's rail network.

[66][67] From 2025, services will cease to stop at Flinders Street, Southern Cross, Flagstaff, Melbourne Central, Parliament, Richmond, and South Yarra stations due to the opening of the Metro Tunnel.

The Cranbourne line uses a fleet of electric multiple unit (EMU) High Capacity Metro Trains operating in a seven-car configuration, with three doors per side on each carriage and can accommodate of up to 1,380 passengers in each train-set.

Shared with the Pakenham, Sunbury, and Airport lines, the rolling stock will consist of 70 High Capacity Metro Trains (HCMT), once fully delivered.

[73] In compliance with the Disability Discrimination Act of 1992, all stations that are new-built or rebuilt are fully accessible and comply with these guidelines.

This number is expected to grow within the coming years, as a network restructure associated with the opening of the Metro Tunnel is completed by 2025.

[79] Since its re-opening in 1995, the Cranbourne line had used a fixed-block, three-position signalling system designed for lower frequencies and less services.

These works valued at $1 billion includes the roll-out of 55 kilometres (34 mi) of HCS and communications systems on the aforementioned lines, allowing an increase in reliability and frequency.

[82] The line will be equipped with Bombardier's CityFlo 650 communications-based train control system, which will enable operation at 2–3 minute headways.