Built to serve the crowds of the Expo 67 exhibition, the line now forms a key link between Downtown Montreal, the South Shore and the city of Longueuil.

[1] The line then heads northeast, gradually ascending as it passes under St. Lawrence River, to the cut and cover Jean-Drapeau station on Île Sainte-Hélène.

Departing Jean-Drapeau, the line descends to pass underneath Le Moyne Channel, Île Notre-Dame and the St. Lawrence Seaway, before ascending at gradients of 6.3% to the terminus at Longueuil–Université-de-Sherbrooke in Longueuil.

[1][2] In November 1961, Montreal City Council decided to build a Metro network, however the Yellow Line was not part of the original plans.

[6] On August 6, 1963, the decision to build the line was approved by Montreal City Council in a special meeting,[7] at an estimated cost of $17 million.

[13] Following the closure of Expo 67, the line serves the La Ronde amusement park, events at Parc Jean-Drapeau (such as the Canadian Grand Prix) as well as allowing connections to Longueuil and the South Shore.

[20] As of 2023[update], construction work is underway to make the Yellow Line platforms at Berri–UQAM accessible, despite the technical challenge of excavating and building new elevators 28 metres (92 ft) below street level.

[21] In 2009, Premier of Quebec Jean Charest announced $12 million to undertake Metro extension feasibility work.

[29][30] In January 2024, CDPQ Infra announced it was withdrawing its proposal to build a line on the South Shore, leaving the local mayors to coordinate with the soon-to-be created provincial government agency for large public transit projects.

[33] In 2018, Québec solidaire proposed a two station extension to McGill, to relieve congestion at Berri–UQAM and connect to the under construction Réseau express métropolitain.