The 23-year-old underwent his medical and signed his contract on Saturday morning, where he will wear the No. 19 shirt for Pablo Machin's side.
"I arrived at this club when I was 16 with the hope of a boy and with the dreams that everyone who goes into La Masia has," his message read.
"I lived the reality of growing and sharing a dressing room with the greats and although I had to leave on two occasions, I came back and I kept trying.
"Now I must go again, this time dedicating myself to another club who also love football.
"I will always carry you in my heart."