Viviani began his pro career at Liquigas-Doimo, where he stayed as the team moved through its various guises to eventually become Cannondale, and signed for Team Sky in 2015.
His stage wins prior to his arrival at Sky include the Tour of Turkey, USA Pro Challenge, Tour of Beijing, Tour de San Luis, Critérium du Dauphiné and Tour of Britain. He has also won three European titles on the track, as well as a silver medal for Italy at the World Championships in 2011.
Since joining Quick-Step Floors, his dominance became apparent, with 4 stage wins in his home tour and winning the points classification. The same season he won the Italian national RR and claimed 3 stages at La Vuelta.
Whilst 2019 started with several wins, Viviani failed to claim any stages in the Giro and a singular victory at the Tour de France.