Movistar, Spain's best-funded professional squad, said Cobo signed a two-year deal to return to the team for which he previously competed during a single disappointing season when they were sponsored by Caisse d'Epargne.
"I raced for them in 2010 and things did not go as expected. Both of us were disappointed and I am sure this time it will work out better," Cobo told reporters.
In September, Cobo claimed an unexpected win in the 2011 Vuelta, Spain's most important road cycling race, after he lost British rivals Chris Froome and Bradley Wiggins to solo to victory in the country's most difficult single climb, the Angliru.
But not even the dramatic Tour of Spain win could save Cobo's Geox squad, which announced it was pulling out of cycling in October after a year's sponsorship, leaving around 25 riders stranded.
However, Cobo's last-minute transfer to Movistar could strongly boost his chances of a repeat win in the 2012 Vuelta.
"I'm really satisfied because (the) Movistar Team is one of the biggest squads in the world and will give me a chance to be in the most important races in the calendar," Cobo said.
Cobo's deal with Movistar will see him race alongside Valverde, the 2009 Tour of Spain winner, who re-joins the team following a two-year absence from the sport after he was implicated in a blood doping scandal.
Cobo and Valverde will be hoping to replicate Movistar's golden years when the squad guided cycling greats Miguel Indurain and Pedro Delgado to victory in 10 major Tours, including six Tours de France.
Formed in 1980 with sponsorship from Reynolds, a metals manufacturing company, and backed by Spanish bank Banesto, it won the Tour de France five times and the Giro d'Italia twice through Indurain.