The 20-year-old signed a four-year deal, having been unable to command a regular first-team place under new manager Juergen Klopp.
Bournemouth did not reveal the fee but media reports said it was a club record 15 million pounds.
“We’re looking forward to seeing him to grow, he’s a huge prospect,” Bournemouth chief executive Neil Blake said in a statement on the club’s website.
“We’ve now signed five players this summer, all of whom have an abundance of potential.
“It shows that we’re serious about nurturing talent at this football club and we have the long term in mind when we say we want to stay in the Premier League.”
Source: GNA/dpa/News Ghana