Atsu has signed a five-year contract and joins the Blues for a reported £3.5million fee.
Atsu has been loaned out to Dutch side Vitesse Arnhem for the rest of the season.
Atsu made 17 appearances for Porto in the league last season.
Atsu has signed a five-year contract and joins the Blues for a reported £3.5million fee.
Atsu has been loaned out to Dutch side Vitesse Arnhem for the rest of the season.
Atsu made 17 appearances for Porto in the league last season.
