Chelsea have appointed Graham Potter as their new head coach.
Potter succeeds Thomas Tuchel at Stamford Bridge after the club parted ways with the German on Wednesday.
Chelsea have agreed to pay Brighton a release clause to allow them to take the highly-rated English manager to London.
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Potter will take charge of the team immediately, and told the club website he wants to "develop a team and culture fans can be proud of".
"I am incredibly proud and excited to represent Chelsea FC, this fantastic football club," he said.
"I am very excited to partner with Chelsea’s new ownership group and look forward to meeting and working with the exciting group of players and to develop a team and culture that our amazing fans can be proud of.
"I would also like to place my sincere thanks to Brighton & Hove Albion for allowing me this opportunity and in particular Tony Bloom and all the players, staff and supporters for their continued support during my time at the club."
Chelsea chairman Todd Boehly said: ‘We are thrilled to bring Graham to Chelsea. He is a proven coach and an innovator in the Premier League who fits our vision for the club. Not only is he extremely talented on the pitch, he has skills and capabilities that extend beyond the pitch which will make Chelsea a more successful club.
"He has had a major impact at his previous clubs and we look forward to his positive impact at Chelsea. We look forward to supporting him, his coaching team and the squad in realising their full potential in the coming months and years."
Brighton chairman Tony Bloom said: "I am very disappointed that Graham will be leaving us. He has done exceptionally well over the past three-and-a-bit seasons, he is an exceptional head coach and an exceptional person. He will be hugely missed at our football club."
The 47-year-old forged his managerial career in Sweden, spending seven years at Ostersund.
Potter guided the Swedish club from the fourth tier into the Europa League before being appointed manager at Swansea in June 2018.
Brighton paid the Welsh side a reported £3 million in compensation to secure his services a season later, and have since finished 15th, 16th and ninth under Potter.
Tuchel was sacked after a mixed start to the season amid reported off-field tensions with the club's new ownership.
A statement from Chelsea suggested that it was the "right time" to make a change despite spending more than £250 million on new players during their first summer transfer window under the ownership of Boehly.
A consortium led by American businessman Boehly bought the club from Roman Abramovich in May.
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