Sagan, 24, has won the Tour de France green jersey for the points classification winner three times, and will join twice Tour winner Alberto Contador at the team owned by Russian entrepreneur Oleg Tinkov.
"Peter is without doubt one of the biggest talents in cycling and one of the biggest names already," team manager and former owner Bjarne Riis said in a statement after winning the race to sign Sagan.
"He has a winning mentality, he's visible and active in the finales and he, without doubt, has the ability to bring home victories."
Sagan has won four Tour stages in total, but was unable to add to his tally this year despite his dominance of the green jersey competition, complaining that his rivals worked against him at the end of stages.
"It will be exciting to work with Peter also for me personally," Riis added.
"He has a huge talent and he's already very strong but I believe he has even more potential than what we've seen so far.
"He still has a lot to learn about the tactical aspects of cycling to fully optimize his power but I believe that we are fully able to help him improve even more.
"Next year, we'll have a very strong team to support him and to aim for big wins throughout the season."
Tinkoff-Saxo won three stages at this year's Tour de France, while Poland's Rafal Majka claimed the mountain classification after Contador crashed out.
- Sports & Recreation
- Alberto Contador
- Tour de France
- Bjarne Riis