Sastre, who won the Tour de France in 2008 and has twice been runner-up in the Vuelta, joins Russia's two-time Vuelta champion Denis Menchov in leading the team's challenge.
“For me the Vuelta is a very important event," said Sastre.
"I feel like health is on my side, as compared with the first part of the season, when I had several problems. I’ve finally found the momentum I’ve been striving for, both in training and during races. This is essential for me to take on a three week race. I’m hoping I can close out the season in the best way possible.”
Menchov, who won the race in 2005 and 2007, said the Vuelta was a race he "really loved."
"I’m starting out with the objective of obtaining the maximum result, although it won’t be easy," he said.
"The route is gruelling and I’ll be going up against some very competitive rivals. Fortunately, I’ll be able to count on the support of some excellent riders. I think our squad is well equipped to put in a good race.”
In addition to Sastre, the team contains three other Spaniards - David Blanco, Juan Josè Cobo and David De la Fuente - another Russian, Dimitryy Kozontchuk, Colombian pair Fabio Duarte and Mauricio Ardila and Austria's Matthias Brandle.
The Vuelta starts on Saturday with a 13.5km time trial in Benidorm, and finishes in Madrid on September 9.
GEOX-TMC Vuelta team: Mauricio Ardila (Col), David Blanco (Sp), Matthias Brandle (Aut), Juan Josè Cobo (Sp), David de la Fuente (Sp), Fabio Duarte (Col), Dimitryy Kozontchuk (Rus), Denis Menchov (Rus), Carlos Sastre (Sp).