He played 115 Primeira Liga games for Vitória de Guimarães, Porto and Rio Ave, winning a league title with the second of those clubs in 2017–18.

Born in Lisbon of Cape Verdean descent, Hernâni started playing with local Atlético Clube de Portugal.

In the 2010–11 season he contributed 21 appearances – only one start – to help the club return to the Segunda Liga after a lengthy absence, making his debut in the competition on 4 September 2011 by coming on as a 73rd-minute substitute in a 2–1 away win against C.D.

[5] Hernâni joined FC Porto on the last day of the 2015 January transfer window, after scoring four goals for Vitória in the first half of the campaign.

[19] Having played just five games – all off the bench – in his only season in the Canary Islands, he returned to his country's top flight on 9 August at Rio Ave F.C.

[21] Hernâni terminated his contract with Rio Ave by mutual agreement in January 2024 and went back to Saudi Arabia, signing with Al-Najma SC of the First Division League until 30 June.