The 23-year-old Belgian joined the Owls from Manchester United in January and made 11 league appearances last season.
He could make his debut in Sunday's Championship opener with Middlesbrough.
Boss Simon Grayson told the club website: "He had a fantastic upbringing at Manchester United, learning and developing from the best in players and staff in the world."
"He can play as an orthodox right-back and as a wing-back," Grayson added.
"When you've been a Manchester United player you have got to be able to handle the ball; we want him to join in with play when needed to as well as defend."
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Preston North End have signed Sheffield Wednesday full-back Marnick Vermijl on a season-long loan deal.