[3] St. Marys station opened on 1 May 1862 as the interim terminus of the Main Western line when it was extended from Rooty Hill.

[6] The study's final report was released in March 2018 and included a proposal to construct a "North-South Link" from Schofields to Macarthur via the airport.

The waiting room has no wall on the rail side and extends by a wide corrugated metal awning supported on timber posts and beams featuring exposed rafters and decorative timberboards at both ends.

Each wing features one face brick tall chimney with corbelled top above the relatively new corrugated metal roof of the building.

A pitched modern metal canopy with awnings on both elevations supported on steel frame and columns extends on Down and Up ends of the building.

The central waiting room features painted brick walls, timber board ceiling lining and tile floor finish.

[3] External: A Subtype 2 rectangular face brickwork goods shed with corrugated metal pitched roof.

Modern timber bench seating, lighting, amenities, vending machines and aluminium palisade fencing are other features on the platforms.

Platforms are accessible via stairs and lift towers leading to the footbridge, where the 1995 overhead booking office and concourse are located.

Sets of stairs to each street and platform provides access together with two modern lift towers at either end of the footbridge.

Both sides of the footbridge, which accommodates the concourse and the overhead booking office, are enclosed by steel framed glass panels.

It is placed on an octagonal concrete foundation and currently preserved as an industrial archaeological item within a brick dwarf wall and aluminium palisade fencing around its perimeter.

[3] The current bus interchange opened on 7 March 2022 at the former Veness Place car park (closed in August 2021) on the south side of Station Street, replacing the previous bus interchange on the other side of Station Street which was closed for Sydney Metro construction.

The station, in particular the signal box, has strong associations with the operations of the once important rail system to Dunheved and Ropes Creek, and with the development of local industry and residential expansion of St Marys after 1942.

The place has research and technical potential for its ability to provide evidence on the construction techniques and operational system of the NSW Railways in the 1880s and during the World War II period.

[3] St Marys Station Group has representative significance combining a range of buildings and structures dating from the 1880s and World War II period to the present day including the station building, goods shed, signal box, crane and footbridge substructure.

[3] St Marys railway station was listed on the New South Wales State Heritage Register on 2 April 1999 having satisfied the following criteria.

St Marys Station Group is of historical significance as one of the early railway stations opened when the Great Western Railway was extended from Parramatta and for its role during World War II in handling the increased traffic for the American ammunition and general store built at Ropes Creek.

[3] The place is important in demonstrating aesthetic characteristics and/or a high degree of creative or technical achievement in New South Wales.

[3] The place has potential to yield information that will contribute to an understanding of the cultural or natural history of New South Wales.

St Marys Station has research and technical potential for its ability to provide evidence on the construction techniques and operational system of the NSW Railways in the 1880s and during the World War II period.

It provides physical evidence of railway operations and policies that were established and shaped in accordance with the politics and war industries.