Valverde, 30, was quoted as saying in a statement on Tuesday that he and his advisors consider the CAS ruling "totally unjust and illegal."
He said he would bring the case before the Federal Supreme Court (Tribunal) of Switzerland, and, if necessary, before the European Court of Human Rights.
The Swiss-based CAS said on Monday it granted a request by the ruling cycling body UCI and the World Anti-Doping Agency (WADA) to extend a ban on racing in Italy, imposed last year by the nation's Olympic Committee, to a worldwide ban.
Valverde was retroactively banned from January 1, 2010, but he was allowed to keep his results until then, including the 2009 Vuelta title.
Valverde was implicated in evidence seized by Spanish authorities in 2006 in connection with Operation Puerto case centering on doctor Eufemiano Fuentes.
The Italian authorities banned Valverde for two years via a Spanish blood bag containing EPO that was attributed to him via DNA tests. He never failed a doping test.
The UCI and WADA have expressed their satisfaction with the verdict, while Spain's highest sports body CSD and the nation's anti-doping agency AEA said they will respect it.
Spanish cycling federation (RFEC) supremo Juan Carlos Castano said his body has to accept the ruling and lamented that Spanish justice authorities have refused up now to share Operation Puerto evidence with sports organisations.