The player is hoping to reignite his career after a number of frustrating, injury-hit years and had been training with Jason Tindall’s squad in recent weeks.
Wilshere told afcbTV: “It feels great to be back and I can’t wait to get started.
“From the minute I walked through the door three weeks ago, it felt natural and like I had never been away.
“I’ve been impressed by the coaching staff, the way they work and the ambitions of the club to get back in the Premier League.”
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Wilshere made 27 appearances in his previous spell with Bournemouth, helping the club to their best finish of ninth in the Premier League.
Bournemouth boss Jason Tindall is pleased with his new signing (Andrew Matthews/PA)
He joins a club now third in the Championship following their relegation last season.
Manager Tindall said: “I’ve been really impressed with Jack in the short time he’s been here and he feels he still has unfinished business here with the way his time ended with the injury.
“Whilst he was here it was the best finish in the Premier League the club has had and Jack was a huge part and reason for that.
“To add someone of Jack’s quality to the group of players we have got can only be a good thing for the second half of the season.”
Bournemouth are in action on Tuesday as they travel to Derby in the Championship.
Chief executive Neill Blake said: “I’m delighted that Jack has returned to the club on a permanent contract.
“He is a fantastic footballer whose quality has been evident since breaking into the Arsenal first team as a 16-year-old.
“In the three weeks he has been training with us we have seen hunger and desire to match his undoubted talent, and he will add some great attributes to our midfield over the coming months.”
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