The versatile defender spent last season with Crystal Palace but went into pre-season hoping to convince Jose Mourinho to keep him in Manchester this season.
Sergio Rico, who arrived from Sevilla on loan on deadline day, was expected to be the club's first-choice keeper, but the 24-year-old, who has been a regular in La Liga, will have to settle for a place on the sidelines having trained just once with his new team. Newly promoted Fulham beat competition from Bundesliga side Hertha Berlin for his services, sources told ESPN FC.
Fulham appears well suited for the rigors of the Premier League and should be able to benefit from the support of the home crowd in their first game back since 2014.
"That discussion I know has been going on and I get occasional updates, as far as I am concerned that is private business between Wilf [Zaha] and the club, but I am confident that they'll find the solution that everyone is happy with". "I'm excited to start training, to meet all my teammates and, above all, to enjoy the season that starts this Saturday".
In the 2016/17 campaign, Vietto played for Sevilla and a year ago he played the second half of the season for Valencia.