[1] Operated by Metro Trains Melbourne, it is the city's third-longest metropolitan railway line, at 42.7 kilometres (26.5 mi).

[3] Trains on the Frankston line run with a two three-car formations of Comeng, Siemens Nexas, and X'Trapolis 100 trainsets.

[6] Since the 2010s, due to the heavily utilised infrastructure of the Frankston line, significant improvements and upgrades have been made.

[8] Mordialloc station was officially opened on 19 December 1881 by Sir Thomas Bent, who was the Minister of Railways, and later becoming the Premier of Victoria between 1904 and 1909.

[8][9] The first train to arrive at Mordialloc was a special service from Princes Bridge, which collected school children from the Brighton area.

[12] In 1885, a number of level crossing removal works occurred between Flinders Street station and South Yarra due to an increase in freight and passenger operations.

In 1915, the line between South Yarra and Caulfield was quadrupled, as part of level crossing removal works.

[16][17] The electrification of the line allowed for the introduction of Swing Door electric multiple unit trains for the first time.

[19] Triplication of the line from Caulfield to Moorabbin from two to three tracks was announced by Transport Minister Steve Crabb in 1984, at a cost of A$10 million.

Construction of the additional track was designed to increase peak hour capacity and to provide express services on the corridor, with time savings of more than 10 minutes from Frankston.

[22] In 1981, Frankston line services commenced operations through the City Loop, after previously terminating at Flinders or Spencer Street stations.

[23] The commencement of operations involved the service stopping at three new stations—Parliament, Melbourne Central (formally Museum), and Flagstaff.

[24] The Loop follows La Trobe and Spring Streets along the northern and eastern edges of the Hoddle Grid.

At the conclusion of the project, all level crossings between the city and Frankston station will be full grade operated through a variety of methods.

[36] Stage 4 of the Network Development Plan – Metropolitan Rail proposed that the Craigieburn and Frankston lines be joined via a reconfigured City Loop sometime in the 2030s.

[37] In 2013, as part of Public Transport Victoria's Network Development Plan for metropolitan rail, an extension of the Frankston line to Baxter was earmarked to begin in the "long-term", which would equate to at least 2033.

[38] In 2018, the Liberal Party announced a project to extend electrified services to Baxter during the 2018 state election.

[42] The incumbent Andrews government made no commitments to the Baxter rail extension, instead continuing construction on level crossing removal works along the Frankston line.

[42] The 2022 state election resulted in another Labor victory, with the Andrews government pushing ahead with these works, with the extension to Baxter remaining stagnant ever since.

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

[54] From Mentone, the line is never more than ~1 kilometre (0.6 mi) from the eastern shore of Port Phillip Bay, and runs alongside the Nepean Highway for much of its length.

[57] The Frankston line uses three different types of electric multiple unit (EMU) trains that are operated in a split six-car configuration, with three doors per side on each carriage.

The primary rolling stock featured on the line is the Comeng EMUs, built by Commonwealth Engineering between 1981 and 1988.

The new trains will include features designed to increase passenger comfort like quicker doors, allowing for reduced boarding times, passenger information systems to display relevant information about the train and its journey, designated bicycle storage areas, and 6 cars that are fully walk through.

[63] 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 with the completion of level crossing removal works on the corridor by 2029.