Hamilton Highway is a rural highway through the Barwon South West region of Victoria, Australia, linking Geelong and the town of Hamilton. through the Parliament of Victoria provided for the establishment of the Country Roads Board and its ability to declare Main Roads, taking responsibility for the management, construction and care of the state's major roads from local municipalities. (Geelong-)Inverleigh Road from Geelong to Inverleigh was declared a Main Road on 16 March 1914, and Cressy-Inverleigh Road from Inverleigh to Cressy was declared a Main Road on 9 June 1925.
The passing of the Highways and Vehicles Act 1924 provided for the declaration of State Highways, roads two-thirds financed by the state government through the Country Roads Board. Hamilton Highway was declared a State Highway in the 1959/60 financial year, from Geelong via Cressy and Mortlake to Hamilton (for a total of 143 miles), subsuming the original declarations of Geelong-Inverleigh Road and Cressy-Inverleigh Road as Main Roads; before this declaration, this road was also referred to as Geelong-Hamilton Road.
A new bridge over Woady Yaloak River in Cressy was opened in 1995, at a cost of $2.86 million, adjacent to and replacing a structure built in 1854 and rebuilt in 1880 after fire damage, retained but now closed to vehicular traffic.
Hamilton Highway was signed as State Route 106 between Geelong and Hamilton in 1986; with Victoria's conversion to the newer alphanumeric system in the late 1990s, this was replaced by route B140.
The passing of the Road Management Act 2004 granted the responsibility of overall management and development of Victoria's major arterial roads to VicRoads: in 2004, VicRoads re-declared the road as Hamilton Highway (Arterial #6780), beginning at Latrobe Terrace at Geelong and ending at Glenelg Highway in Hamilton.