The União was the sixth ship of her class ordered by the Brazilian Navy, on 20 September 1970.

[1] In 2003, União underwent the modernization process, which provided the vessel with an increase in its operating life.

From 14 November 2011 to 14 May 2012, União was the flagship of UNIFIL's Maritime Task Force, leading three ships from Germany, two from Bangladesh, one Greek, one Turkish and one from Indonesia.

[3] From 18 June to 20 August 2022, União performed Operation "Guinex II", which saw her patrol the waters around the Gulf of Guinea and visit several Western African countries such as the Ivory Coast, São Tomé e Príncipe, Cameroon, Nigeria and Cape Verde, helping train local forces in boarding and anti-piracy operations.

[4] In 2023, the frigate, accompanied by her sister ship Independência and the submarine Tikuna, conducted joint exercises with the destroyer Sarandí and the offshore patrol vessel Bartolomé Cordero of the Argentine Navy.