Bournemouth have completed the signing of Wales international defender Chris Mepham from Brentford for an undisclosed fee believed to be £12million.
Centre-back Mepham has agreed a "long-term" contract with the Premier League club after undergoing a medical on Tuesday.
The 21-year-old, who has been capped four times by his country, was a long-standing target of Cherries boss Eddie Howe.
"It's taken a while to get my signature on the dotted line but it's been worth the wait," Mepham told afcbTV.
"There's so much to like about this club, not least the manager. Eddie Howe is a fantastic manager and what he's done here is remarkable, so to be working under him every day is a really exciting prospect.
"I'm still young and have lots to learn and develop on my game but I can't wait to get started, to meet everyone and to get out on the training pitch."
Mepham appeared 48 times in all competitions for Brentford, having made his debut in January 2017, scoring once in the Sky Bet Championship.
The centre-back started 22 of the Bees' 28 league games this season and played in Wales' Nations League games against the Republic of Ireland and Denmark in September.
He becomes Bournemouth's third arrival of the January transfer window following the loan signing of right-back Nathaniel Clyne and the £19million purchase of striker Dominic Solanke.
Bournemouth boss Howe said: "Chris is a talented, young defender who has been on our radar for some time, so I am delighted he is finally our player.
"He has shown a huge amount of potential in his time at Brentford and while playing for Wales, and we believe this is the perfect environment to continue his development.
"Chris is a good defender and comfortable on the ball, and we believe he will be a great addition to the squad here."