[5] On 25 August 2016, Fernandes signed a four-year deal with English club West Ham United for a fee of £5 million.

[6] He made his West Ham debut on 25 September 2016 in a 3–0 home defeat by Southampton, coming on as an 82nd-minute substitute for Mark Noble.

[8][9] On 13 August 2018, Fernandes joined Italian side Fiorentina on a one-year loan deal with an option to buy.

[10] On 3 June 2019, Fernandes joined Bundesliga side Mainz 05 on a four-year deal for an undisclosed fee.

[11][12] On 17 August 2019, he made his full debut for the club in the league season opener against SC Freiburg, starting and playing 84 minutes of a 3–0 loss while picking up a first-half yellow card.