Leicester have signed Belgium international Youri Tielemans from Monaco on a four-year deal for a club record £40m.
Tielemans, 22, scored three goals and provided four assists in 13 Premier League appearances on loan at the Foxes last season.
He is Leicester’s third summer signing after Ayoze Perez joined from Newcastle and James Justin arrived from Luton.
“I really can’t wait to get started again with this club,” said Tielemans.
“I believe that we have the talent in our squad to achieve something special and for any player, that’s an exciting thing to be a part of.”
Tielemans became Claude Puel’s final signing as Leicester boss when he joined on loan in January.
Puel was sacked the following month and replaced by Celtic manager Brendan Rodgers.
“I’m delighted that Youri has chosen to be part of Leicester City’s journey,” said Rodgers. “It’s an incredibly exciting time for this football club and to be able to bring players of Youri’s quality here is an indication of the hunger for success we have here.
“Youri fit brilliantly into the squad last season. He’s already shown that he’s capable of making an impact in the Premier League and he adds another option to an incredibly talented group of players here at Leicester City.”