The 32-year-old Italian joined the team in 2015 after two seasons with Team Sky following prior stints with Quick-Step and Liquigas. The Tour de France is the second Grand Tour of the season for Cataldo after riding to 14th place overall at the Giro d'Italia in May.
"I am really happy to renew my contract with Astana Proteam. This is a great team, which is developing year by year, always setting the highest goals at the Grand Tours. I like this so much, because I find a good motivation in moving ahead in my progress as a rider and staying in the successful team with big ambitions, said Cataldo.
Although Cataldo is yet to win a race in Astana colours, he was a key domestique in 2015 for Aru at the Giro d'Italia where placed second and then at the Vuelta a Espana where Aru claimed the overall victory.
Astana general manager Alexandr Vinokurov explained that during his three seasons with the team he has proven himself to be a valuable domestique.
"I like the style and sports character of Dario. He is a real fighter on the road, who can be a super domestique for the leader, but in the same time he can take a responsibility in the race on himself," Vinokurov. "We saw it in the Giro just a few weeks ago. I am happy to provide Dario a new contract for the next two seasons. We see his progress and in the nearest future he can reach some nice results."
Cataldo joins Luis Leon Sanchez in expanding his contract with the team after the Spaniard put pen to paper in early-June. Aru is out of contract at the end of 2017 and is currently considering his options with Trek-Segafredo emerging as a possible destination.