Diogo Mendes was born in Faro on 24 January 1998 and joined Benfica's academy, becoming a mainstay of the B team in the Portuguese second division as a defensive midfielder. Composed in possession and a reliable screen for the back four, he captained the reserve side.

He was registered with the first-team squad for the 2019-20 season but did not establish himself, and in July 2021 joined Marítimo. Three years later he moved to Romania with Rapid București. He has been capped by Cape Verde.