Whilst at Universal-owned Polydor, Shymansky signed La Roux, Jamie Woon and other notable acts.
However, he is perhaps best known for his seven years at 19 Management, where he was credited with discovering and looking after Amy Winehouse during her most successful period.
Previous to his role at 19, Shymansky worked at Brilliant PR and Delirious Records.
"I first met Nick over a decade ago when I walked into the 19 office," said Island co-president Darcus Beese. "He was managing a girl called Amy Winehouse. We've been friends ever since. In fact I tried him to get to come to Island a few years ago but the timing wasn't right.
"Like all good trappers I've finally got my man and I'm convinced that with Nick's passion and his talent for artist development he could not be joining Island at a better time for us and for him."
Island's head of A&R Louis Bloom added: "Nick is one of the most respected and well-liked A&R men in the industry and will be a fantastic addition to the team here at Island.
"His reputation as a music man, his enthusiasm and his impeccable taste will ensure that Island continues to be a welcome home for new artists. It's also great to know that we will no longer be competing with him over new acts."