Fernandes has joined from FC Sion and was introduced to his new supporters on Thursday.
The 20-year-old has moved from Sion in a deal worth a reported £5.5 million and was announced and brought onto the London Stadium pitch before the Europa League play-off round second leg against Astra Giurgiu on Thursday night.
Fernandes becomes the Hammers tenth signing of the summer in total, and the second central midfielder to arrive after former Borussia Moenchengladbach star Havard Nordtveit.
The younger cousin of current Switzerland international and former Manchester City and Leicester City man Gelson Fernandes, the young star will be hoping to leave his own mark on English football.
However, he is likely to face a big challenge to break into a regular first-team spot in midfield with the wealth of options that Slaven Bilic has at his disposal.
Nordtveit is joined by captain Mark Noble, Cheikhou Kouyate, Pedro Obiang, and Dimitri Payet in a central role, whilst summer signings Gokhan Tore, Sofiane Feghouli, and Andre Ayew, and Manuel Lanzini and Michail Antonio can all occupy a wide midfield role.
Regardless, some Hammers fans were keen to welcome the new man to the London Stadium and expressed their hopes that he can immediately play a significant first-team role.
West Ham completes signing of Fernandes from FC Scion @WestHamUtd last year team is amazing but this year it truly amazing.— Anwar Nadaf (@Anwar_ManUtdfan) August 25, 2016
Welcome Fernandes become one of our legends COYI !!!— willem velthuijs (@lepneuvide) August 25, 2016
Edilmilson Fernandes just revealed to the fans⚒— Kyle (@KyleWHUFC) August 25, 2016
Others, however, were less enamoured with the lack of prestige surrounding Fernandes' name.
@WestHamUtd why so many midfielders? Carroll is injured we've got Payet, we are lacking in firepower— Sparky (@daveycunningham) August 25, 2016
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