The 23-year-old left the Reds’ pre-season tour of Hong Kong on Wednesday, and underwent a medical in Portugal the following day, after agreeing personal terms.
Liverpool have now confirmed Stewart’s exit, three years after the Englishman joined on a free transfer from Tottenham.
Stewart made 20 appearances for the Reds’ first team, including 11 last season, but saw his opportunities increasingly limited due to the competition for places under Jurgen Klopp.
Reports suggest Stewart’s move could see Liverpool eventually receive £8 million, depending on various add-ons.
Stewart’s move was confirmed shortly after Liverpool announced the signing of left-back Andrew Robertson, with the Scottish player arriving in the opposite direction.
Best of luck, Kevin.