The aim of the union was the creation of a strong metropolitan center with pooled resources, an internationally competitive profile and unified management of common infrastructure.

The intent to form the union was formally stated by the mayors of the participating cities, who signed a declaration to this effect on 9 January 2006 in Świętochłowice.

[8] The Union's registration was signed by the Ministry of Internal Affairs and Administration of the Republic of Poland (Polish: MSWiA) on 8 June 2007 with the city of Katowice.

[9] On 1 July 2017 a new sui generis entity, the Metropolis GZM (Polish: Górnośląsko-Zagłębiowska Metropolia), was created.

[14] Towns of Będzin, Czeladź and Knurów declared their willingness to join the Silesian Metropolis, but due to legal issues[citation needed] canceled their candidacy.