Interline Bus Services was formed when the Oliveri family purchased route 102 Campbelltown Hospital - Macquarie Fields from Herbert Harrison on 1 September 1961.

[1] On 1 June 1989, it merged with Oliveri's Transport Service, Green Valley with both renamed Metro-link Bus Lines.

[1][4][5][6] In August 2002, Southern Cross Transit, Karana Downs, was purchased by the Oliveri family and is now the sister company of Interline.

In the 1980s the Ingleburn Bus Service fleet consisted of Bedford YMT3s and Leyland Super Vikings and Tigers, two of which were configured as coaches.

In February 2021, Interline received their first electric buses, with ten BCI CitiRiders rolled out into service on two routes.