Marc Cucurella, a defender from Spain, has been signed by Chelsea from Brighton for more than £60 million.
The 24-year-old left defender has agreed to a six-year contract. In his lone season with the Seagulls, he played in 38 games and scored one goal.
“I’m really happy. It’s a big opportunity for me to join one of the best clubs in the world,” said Cucurella.
“I’m going to work hard to be happy here and help the team.”
It surpasses Ben White’s £50 million move to Arsenal last summer as the highest-ever sale for Brighton.
Cucurella, a member of the Barcelona academy, has one senior cap for Spain and participated in the under-23 squad that took home silver at the 2020 Tokyo Olympics.
Cucurella submitted a transfer request after Manchester City displayed interest in him, and Brighton rejected a £30 million offer from the league leaders last month.
“We did not want to lose Marc, but he wanted the opportunity of playing Champions League football with a view to accelerating his progress to Spain’s World Cup squad,” said Brighton manager Graham Potter.
“He had an excellent first season in the Premier League, deservedly winning both our player of the season awards, and has been an absolute pleasure to work with over the past 12 months.”