Danilo |
"I'm really happy to arrive to this great club," Barbosa said on the club's official website. "This is a moment of great happiness for me to face this challenge.
"Valencia is a club with a lot of history and I want to be a part of it.
"I'm going to give everything for this jersey."
Captain Danilo shone for Brazil at the under-20 World Cup in New Zealand last month, winning the Silver Ball as the second-best player of the tournament as the South Americans finished runners-up to Serbia.
"It is pleasing to announce the signing of another young player of quality for the Valencia family," club chairwoman Chan Lay Hoon said.
"I know that many clubs were interested in him but I am very happy he chose to join our project," she added.
"Danilo was one of the best players at the Under-20 World Cup, he is the captain of the Brazil team and I think this shows the character he has."
Following last year's takeover by Singapore billionaire Peter Lim, Valencia are ambitious to return to the top in Spain and Europe after a period of instability marked by financial troubles and disappointment on the pitch.
They have this month already signed 19-year-old winger Zakaria Bakkali as a free agent and Spain Under-19 international Santi Mina from Celta Vigo.
Los Che, coached by Portuguese tactician Nuno, finished fourth in La Liga during the 2014-15 campaign and will play in next season's Champions League.