The 20-year-old will officially join the Blues from Dutch side NAC Breda on 1st July.
“I am really happy because I think it’s a great opportunity to play in the Premier League,” Valles told Birmingham’s official website.
“I hope Michel will help me settle in and enjoy life in the Premier League. I have watched a lot of Premier League games on TV so I know I will have to work hard.
“A lot of Spanish players have done really well in the Premier League and I hope I can do well too.
“I want to start training now and get a feel for the club but I am going to have to wait until July.
“I am going to work really hard for Birmingham and take my opportunity and do well here. I hope I can help a little bit for Birmingham City.”
