[1] Operated by Metro Trains Melbourne, it is the city's sixth shortest metropolitan railway line at 21.3 kilometres (13.2 mi).

Since the 2010s, due to the heavily utilised infrastructure of the Glen Waverley line, significant improvements and upgrades have been made.

[8][9] The electrification of the line allowed for the introduction of Swing Door electric multiple unit trains for the first time.

[12] The Outer Circle line previously begun its curve south towards Waverley Road and Oakleigh.

[12] The 1950s saw the line undergo major upgrades, including the first centralised traffic control installation in Australia.

[13] On 6 February 1956, the Toorak Road level crossing between Kooyong and Tooronga stations was the first in Victoria to receive boom barriers, replacing hand operated gates.

[15] Also in 1981, Glen Waverley line services commenced operations through the City Loop, after previously terminating at Flinders or Spencer Street stations.

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

[19] These works coincided with the construction of the Monash Freeway which runs alongside the route for part of the journey.

[4][20] The removal of Burke Road, Glen Iris involved the lowering of the rail line and the reconstruction of Gardiner station.

[21] In 2021, the metropolitan timetable underwent a major rewrite, resulting in all Glen Waverley line trains operating via the City Loop alongside Alamein, Belgrave, and Lilydale services.

[22] In 2023, data from Public Transport Victoria found that the Glen Waverley line was the most on-time train service on the network.

[23] Commuters on the Craigieburn line faced the highest train delays, with 10.6% of services arriving late between March 2022 and February 2023.

[23] On the positive side, the Glen Waverley line was the top performer, boasting 97.1% on-time arrivals during the same period.

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

[40] In compliance with the Disability Discrimination Act of 1992, all stations that are newly built or rebuilt are fully accessible.