The midfielder has failed to make a significant impact at the Premier League club and will now drop down a division on a four-year deal once his current deal expires
The former Everton man has struggled to nail down a regular starting place at St James' Park since arriving as one of club's first signings on their return to the top flight in 2010.
|20/1||Bournemouth are 20/1 with Paddy Power to win the Championship next season|
Bournemouth manager Eddie Howe explained the Championship club had to fight off plenty of competition but believes Gosling can help them improve on their 10th-place finish this season.
"He is a box-to-box central midfielder who has lots of energy. He is very good technically and also has a goal in him," he told The Bournemouth Echo.
"He is an attack-minded player who can do all disciplines of the game so I think he will complement our team very well.
"We are looking to build all the time and I think he will give us different options as well. We had to fight off some competition to get him and it is always a good sign when other clubs are interested.
"We are delighted he chose us ahead of them and I think he was attracted by our style of play and our vision for him so, hopefully, it is a good match and we will both get when we are looking for from the signing."
Having struggled with injury early in his time at Newcastle, Gosling made just 36 appearances during his four-year spell at the club.