A goods yard was established in 1882 and soon afterwards plans were prepared to quadruplicate the main line from Sydney to Homebush.

This resulted in a further reorganisation of the Petersham yard so that the main station building was sited "up" on the platform and a new iron footbridge was built to cross the new railway and connect up with a new island platform where the earlier building was demolished and replaced by an elegantly designed curved roof structure.

[3] In 1891, the present subway was built and another island platform building constructed to serve the slow tracks.

[5] This turn back siding was located on land now used for the training college west of the station.

[6] A pedestrian subway was provided in 1892 at the western end of the station, connecting Trafalgar and Terminus Streets.

[3] Upgrades to the station took place in the late 1990s, with the wooden steps on the footbridge being replaced due to their slipperiness in wet weather, a small but high-roofed shed at the east end of the platform being removed for security reasons, and the area under the lower part of the platform stairs also being fenced-off for similar concerns.

In 2021, the station received a significant upgrade, adding lifts and ramps to provide ambulant access to the platform, new bicycle parking, and improved amenities.

[7] In 1967, the Department of Railways granted the New South Wales Rail Transport Museum use of the former goods sidings pending its moving to Enfield.

The Terminus Street elevation is accessed via sandstone steps onto a veranda, supported on cast iron columns with decorative lacework, which spans the extent of the central block.

[3] Recent restorations have included new tuck pointing and the reinstatement of most of the doors and windows to the south elevation, although several remain non-operational.

There is Perspex secondary glazing to the openings on the south side in an attempt to keep out the noise of the passing trains.

[3] A rectangular face brick building (all painted) with a gabled roof and integral shallower sloped cantilevered awnings.

To the north-east and north-west corners there are timber framed multi paned sliding casement windows with security grilles to the exterior.

The building features a Dutch gable roof with fibre cement slates and decorative finials with a timber louvred vent to the gablets.

The entire structure rests on original brick piers, cast iron columns, arches and steel trestles.

It has brick walls and a ceiling made of original concrete slabs reinforced with steel joists.

[3] There are brick retaining walls along Terminus Street made of English bond brickwork from the platform to former station building with an opening for stairs to footbridge.

It is a fine example of a late Victorian Italianate station dating from 1885, and although compromised by later alterations and additions is substantially intact and capable of restoration.

The station is one of a select number of similar buildings designed by the office of the Engineer for the Existing Lines Branch, George Cowdery, with the 1883 iron pedestrian bridge and steps also designed by Cowdery;[3] Petersham railway station was listed on the New South Wales State Heritage Register on 2 April 1999 having satisfied the following criteria.

The extant 19th and 20th century platforms, buildings, footbridge, subway and signal box are collectively able to demonstrate important historical phases of suburban railway development.

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

The 1920s "initial island" platform building is significant with its design showing linear form, gable roof and integrated awnings.

However the footbridge has a number of 1880s elements namely brick piers, cast iron columns, arches, steel trestles and latticework to the deck and overall retains is aesthetic quality.

[3] The place possesses uncommon, rare or endangered aspects of the cultural or natural history of New South Wales.

[3] The place is important in demonstrating the principal characteristics of a class of cultural or natural places/environments in New South Wales.

The signal box at Petersham Railway Station has characteristic features of this type of signal box namely its elevated brickwork base, timber framed, fibre cement clad operating level structure and Dutch gable roof and has a high level of integrity as its original signalling equipment has been retained and it still has original fibre cement slate roof tiles, making it an excellent example.

[3] This Wikipedia article contains material from Petersham Railway Station group, entry number 01223 in the New South Wales State Heritage Register published by the State of New South Wales (Department of Planning and Environment) 2018 under CC-BY 4.0 licence, accessed on 2 June 2018.