The design of the building is attributed to John Smith Murdoch, District Architect with the Queensland Public Works Department, and it was constructed by MS Caskie for the tender price of £3797/18/0.

He arrived in February setting up in a tent, but soon established the Customs Office in a corner of the large store of Byrnes, Basset and Co. located on the riverbank.

[1] The town of Mackay soon began to prosper through the growth of the port, the nearby pastoral holdings, and the plantations along the river which included the beginnings of the local sugar industry.

[1] The design of the Mackay Customs House is attributed to JS Murdoch, District Architect Northern Division for the Queensland Works Department.

Under this team, the Government Architect's Office produced many of Queensland's finest public buildings, including a number for the new Commonwealth.

[1] JS Murdoch was also responsible for the Customs Houses of Maryborough, Bundaberg and Townsville, which exhibit some similarities in style to that of Mackay.

It was reported as featuring locally made bricks, cement and plaster finishing, rolled galvanised iron roof, wood and zinc ceilings, and joinery and fittings of cedar.

The refurbishments truly respected the origins and heritage features of the building whilst giving this iconic landmark a new direction and purpose.

To the front is the semi-circular public area with encircling colonnade, and to each side are offices, separated from the Long Room by a corridor.

The owners have undertaken some minor works including the removal of metal grill gates at the top of the steps to the colonnade entrance, and replaced these with slate grey, steel framed doors with full glazing panels.

The Long Room is a double-height symmetrical space with semi-circular clerestory windows to each side, decorative pressed metal ceiling, and plaster mouldings to the opening surrounds.

The external walls are rendered masonry, and feature stucco panels to the upper sections reflecting the detail of the Customs House.

To the rear of the site is a garage building, with a central bay of brick and lean-to additions enclosed in steel mesh to either side.

The garden has palm trees, lawns and concrete paths, with a bitumen car parking area at the rear of the site[1] Mackay Customs House was listed on the Queensland Heritage Register on 7 February 2005 having satisfied the following criteria.

Community agitation resulted in the earlier timber building being replaced by a new brick structure befitting Mackay's prosperity at that time.

It uses the architectural language of a domestic style of the period, sometimes termed "Federation", which was part of a broader movement searching for a cultural identity for the new nation.

Exterior features include the curved entrance colonnade, "roughcast" stucco panels, gable treatments and tuck pointed brickwork.

It shows a high degree of technical competence, successfully combining picturesque qualities and domestic scale with the traditional formality of government buildings.

Murdoch later had a successful architectural career with the Commonwealth government, playing a substantial role in the development of early Canberra.