[1] Operated by Metro Trains Melbourne, it is the city's ninth longest metropolitan railway line at 32.9 kilometres (20.4 mi).

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

The line was progressively finished within the next two years, allowing trains to travel from Melbourne to Geelong.

[6] In 1857, the Geelong and Melbourne Railway Company (G&MRC) opened the Werribee to Little River section of the line they were building between Newport and Geelong, then in June of that year, they opened the section between Werribee and a temporary station near Newport, known as Greenwich.

[5] This branch was opened by the Altona and Laverton Bay Freehold and Investment Company to encourage people to buy their land in the area.

A portion of the Altona Beach line near Williamstown Racecourse was leased by the Victorian Railways (VR) in 1906 to store race trains.

[9] Duplication of the Werribee line occurred in stages between 1960 and 1968, with the Altona branch converted to Automatic Block Signalling in October 1967.

[18] The rewrite introduced the controversial practice of having trains serving the Altona Loop run as a shuttle service between Laverton and Newport during off peak hours.

[20] In June 2015, the completion of the Regional Rail Link allowed for the rerouting of Geelong and Warrnambool services via the 90 km of new track constructed between Little River and Deer Park stations.

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

[26] The crossing was removed by raising the road onto a bridge above the rail line with upgrades to Aircraft station in conjunction with the project.

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

[37] As part of the Melbourne Metro 2, the Werribee and Williamstown lines would be reconfigured to provide simpler service.

Express services (not via the Altona Loop) would instead be served by trains exiting the Melbourne Metro 2 tunnel towards Werribee (and potentially Geelong).

[6] Geelong Fast Rail was one project identified in the Western Rail Plan as a matter of priority, as it would allow for Geelong and Warrnambool services to travel back via the Werribee line, cutting travel time and allowing electrification of other corridors to occur which are currently being served exclusively by V/Line trains.

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

2 years later in 1859, the government acquired the line and begun operations under the newly formed Victorian Railways (VR).

[11] As a result of the collapse of the 1880s Land Boom, regular services to Altona Beach ceased after August 1890, and the Victorian Government declined the offer of the owners to gift it the line.

In 1917, the owners of the estate entered into an agreement with the Victorian Railways (VR) to provide a regular passenger service, having guaranteed to cover any operating losses.

The route is 32.9 kilometres (20.4 mi) long and is fully doubled tracked from Flinders Street to its terminus, excluding during the Altona Loop.

[53] Most of the rail line goes through built-up suburbs and heavy industrial areas with small pockets on non-urbanised spaces.

[52] The Werribee 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.

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.