Cataldo, 27, joins fellow new recruit Gabriel Rasch at Team Sky after the Norwegian made the move from FDJ-BigMat last week.
The reigning Italian time trial champion leaves Quick-Step after four seasons, having represented Italian outfit Liquigas for two years before his spell with the Belgians.
Cataldo said in a statement: “I was really excited when the opportunity arose for me to come to Team Sky because it is such a big team, and a big organisation. Everybody knows this is the best team in the world, but there is still so much more they want to achieve.
“This last season has been my best and I’ve been able to achieve all my goals. I put in a good ride at the Giro, I was able to win the Italian time trial championship, a stage at the Vuelta, and then competed at the World Championships.
"I want to build on those performances now and set new goals with Team Sky. I can time trial, climb well and also win out of small groups. I am committed to giving my all for this team and will do anything that is asked of me.”
Cataldo won stage 16 of the Vuelta a Espana in August and has eight career Grand Tours on his CV.
He is regarded as an impressive all-rounder, winning the 'Baby Giro' amateur in 2006 and showing his prowess in both time trials and climbs.
Team Sky Sports Director Sean Yates said: “Dario has repeatedly proven that he can be there on the climbs during tough stage races. He has an impressive amount of experience for his age, and moving to Team Sky with a heavy focus on stage racing he will get a lot of support to develop further.
“A rider of his strength has the ability to work for the team leaders, but also has the potential to progress and become a GC contender in his own right.”
- Team Sky