Gédéon-Nicolas-Joseph Bordiau (French pronunciation: [ʒedeɔ̃ nikɔla ʒozɛf bɔʁdjo]; 2 February 1832 – 23 January 1904) was a Belgian architect, active in the second half of the nineteenth century.

His work includes the plans for the Cinquantenaire exhibition parc and buildings, the project for the North-Eastern Quarter, Hotel Metropole and other notable buildings in Brussels.

Bordiau was educated at the Academy of Fine Arts in Brussels and most of his career was concentrated in the Belgian capital.

Working for the public administration, Bordiau was initially a co-designer of the Public Buildings section of the City of Brussels, working under the supervision of and eventually succeeding Poelaert as the Municipal Architect.

In these years Bordiau assures numerous public and private commissions, becoming one of the main protagonists of the architecture in Belgium in the second half of the 19th century.