The striker, who scored four goals in 40 appearances for his home town club over two years, has penned a two-year deal with Michael Laudrup's side.
Starting out as a key member of the Preston squad last season, injury beset his progress before he expressed a desire to play at a higher level.
"I'm delighted to join Swansea," he told the club's official website.
"The club has enjoyed a lot of success over the last few years and their style of football has really caught the eye.
"I'm looking forward to being a part of things and trying to impress the new manager enough to force my way into his plans."
Chairman Huw Jenkins confirmed that Proctor will continue his development in the Swans' Under-21 squad, adding that the striker highlights the club's desire to look to the future.
Jenkins said: "We see it as an important and vital part of the club's long-term future.
"Our aim is to establish a promising group of youngsters under the Under-21 banner who can develop and progress into Michael Laudrup's first-team plans.
"It's important to think about the present, but it's even more important to think about the future."