Basso, no relation to former Giro d'Italia winner Ivan Basso, brings the average age to 27.5, with other young newcomers Egan Bernal, Pavel Sivakov, Kristoffer Halvorsen, and Chris Lawless.
Basso previously rode as a trainee for the Trek-Segafredo squad in 2015, taking third at a stage in the USA Pro Challenge from a breakaway.
Directeur sportif Dario Cioni describes Basso as a sprinter "who can survive the punchy climbs and he has the speed to sprint from smaller groups," and said his signing was based on the results over the past few years.
With the exit of more experienced riders like Elia Viviani, Danny van Poppel, Peter Kennaugh, Mikel Nieve and Mikel Landa, the team is putting more of a focus on young riders, despite also signing Jonathan Castroviejo, David de la Cruz and Dylan van Baarle.
Team principal Dave Brailsford explained, "We are establishing a group of exceptional young riders at Team Sky. I have no doubt they are going to make a big impact and be an important part of our future.
"I believe the group of home grown and international young talent we are building represents the brightest future we have ever had at Team Sky."
2018 Team Sky rider roster: