Tello made just two starts in the league for the Catalan outfit last term and Luis Suarez arrived at the Nou Camp in a deal worth £75m, which is likely to further restrict the youngster's chances of a starting berth.
"Cristian is happy and eager to show Porto what he can do," Joaquin Tello is reported as saying by Sport-English.com.
"We are ready to pack up our suitcases and say goodbye. He will arrive in Portugal by Tuesday.
"Cristian will take this opportunity. Porto are a big club anywhere, one of the greats in Europe."
Tello made his Barcelona debut in 2011, and has since made 59 appearances, scoring 11 goals.