The original Bonnyrigg bus service began operation in 1951 and was named Calabro's Bus Service. For thirty-eight years, this service was owned and run by three brothers: Frank, John and Baptist.

The business grew from five buses to sixty-eight buses servicing the Bonnyrigg, Fairfield West and Badgery's Creek areas. When the brothers retired in 1989, the service was purchased by Westbus.

Since this time, Westbus Bonnyrigg has continued to expand to a fleet of 83 vehicles and a staff of 131. In 2002, Bonnyrigg opened a new depot site, situated in Bonnyrigg Avenue.