Bournemouth chief executive Neill Blake said: "We have been very impressed by Enes during his time with us over the past few months.
"His work rate and attitude have been exemplary following a long period of injury rehabilitation, and his desire to succeed in Premier League has been clear to see throughout.
"He has proved to be a great addition to the playing squad here and we are delighted to confirm that he joins us on a long-term contract.
"We wish Enes all the best for the summer and look forward to welcoming him back in July."
nal, who made 17 appearances for AFC Bournemouth in all competitions last campaign, told afcb.co.uk: "I'm so happy to be heading back to Bournemouth for the new season.
"I enjoyed testing myself in the Premier League while regaining my fitness, and now I am really excited for the years ahead.
"The project here is something I was keen to be a part of back in January, and I think that we have great potential together to improve further."