Western Port Highway commences at Lyndhurst Interchange, where South Gippsland Highway and the alignment of South Gippsland Freeway meet at Lynbrook, and heads south directly from the southern end of South Gippsland Freeway over a bridge crossing South Gippsland Highway as a four-lane, dual-carriageway road, over the Cranbourne railway line, passing through a set of traffic lights at Portlink Drive and Moreton Bay Boulevard, passing through a roundabout at Glasscocks Road, and traffic lights at Thompsons Road.

[2] Dandenong-Hasting Road was progressively upgraded to a divided highway between South Gippsland Freeway and Cranbourne–Frankston Road during the 1990s, as dramatically increasing freight traffic volumes to and from Hastings necessitated major upgrades, including eliminating the level crossing with the Cranbourne railway line with an overpass in 2001.

[7] The passing of the Transport Act of 1983[8] updated the definition of State Highways.

With Victoria's conversion to the newer alphanumeric system in the late 1990s this was replaced by route A780.

[11] VicRoads had planned to convert the highway to a six- to eight-lane freeway standard between South Gippsland Freeway and about 1.2 km south of Cranbourne-Frankston Road with full grade-separated interchanges at Glasscocks, Thompsons, Hall and Cranbourne–Frankston Roads, and a half-diamond interchange (north-facing ramps only) at Ballarto Road, with a report released in August 2014,[12] however the State Government abandoned any plans for the upgrade, which was estimated to cost $1 billion, in mid-2016.