On Friday, Lewin completed a six-month loan move to the Tykes from Premier League side Derby County.
He told the club's official website: "Simon Davey really impressed me last season and he gave a lot of confidence to go out and play my football. At my age all I want to do is go out and enjoy football and that is something I am sure I will do here. I want to play as many games as possible and I cannot wait to get started.
"I really, really enjoyed my time here last season and cannot wait to get back playing for Barnsley. I loved my time at Barnsley and really like the club, the facilities, the manager, the staff and the supporters so it was an easy decision to come back.
"There was a lot of interest in me from a lot of clubs but it was important that I came somewhere that is moving in the right direction."