The 21-year-old winger will be playing for the Championship club for the rest of the season.
Barker told Preston's official website: "I am delighted to get the deal done, as soon as it came up I was buzzing.
"I have had a couple of successful loan spells and I am looking to build on that. Last year in Scotland I did okay and hopefully this year is the same.
"I hope I can show what I do in the games. Hopefully I can help the team as much as I can, work hard and try and give the fans what they want.
"I spoke to the manager and he did a good job of selling the club to me. He is a manager I think I can improve under; he has a young squad with some older faces and I can't wait to get going."