[1] Operated by Metro Trains Melbourne, it is the city's third shortest metropolitan railway line at 16.2 kilometres (10.1 mi).

During peak hours, the line operates with headways of up to 20 minutes, ensuring frequent service for commuters.

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

[5] In response to 12 months of inaction by the MMA&MRR and pressure from the government and financial backers, the company organised a gala event at Williamstown on 12 June 1854.

[8] Recognising the challenges faced by private companies and the pressing need for railway development, the government took action to address the situation.

On 19 March 1856, despite only small sections being completed, the government intervened and acquired the line, assuming responsibility for its construction and further development.

[11] From Williamstown Pier, passengers could connect to a ferry across Hobsons Bay to Port Melbourne.

[9] The Newport Workshops in Victoria have played a significant role in the railway system, highlighting their importance through various expansion initiatives.

[12] At the peak of operation it was one of Victoria's largest and best-equipped engineering establishments, with up to 5,000 employees on site.

[13] The workshops had their own cricket grounds, and the game of Trugo is said to have been invented by workers on their lunch hour in the 1920s.

In January 2021, a major timetable rewrite resulted in increased frequencies and weekend daytime shuttle services being extended from Newport to Flinders Street.

[19] As part of the reconfiguration, the Werribee and Williamstown lines would instead begin through-running services to Sandringham for the first time.

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

The first section of the line from near Newport to Williamstown Pier was originally opened by the government in 1857 and used by the Geelong and Melbourne Railway Company (G&MR) until the remainder of the government line to Spencer Street (now Southern Cross) opened 2 years later in 1859.

Some sections of the line have been elevated or lowered to remove level crossings, including at Williamstown North station.

[33] The Williamstown line uses diverse 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.

[40] 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.