The Slovenian had been with Jumbo-Visma since 2016, winning three consecutive editions of the Vuelta a Espana as well as this year's Giro d'Italia.
"I am looking forward to this step, even though a team change is kind of like new territory for me. The good memories of when we met years ago made the talks easy," Roglic said in a statement.
"But the decisive factor was that the team is really motivated to work with me and that we hold the same ideas."