"We've taken the decision to appeal to CAS. The opponent will be the International Olympic Committee, Fina and the Russian Olympic Committee," Efimova's agent Andrei Mitkov told R-Sport.
Fina on Monday banned seven Russians, including 2012 Olympic bronze medallist Efimova, from competing in Rio in the fall-out from Russia's rampant state-run doping.
Fina was the first sport to impose bans in light of Sunday's IOC decision, which ruled against a blanket ban on all Russian competitors in Rio, instead leaving it up to individual sports federations to decide whether to accept Russians.
Vladimir Morozov and Nikita Lobintsev, both 4x100m freestyle bronze-medal winners with the Russian team at the 2012 Olympics, and Efimova, who won bronze in the 200m breaststroke in London, were among the seven banned.
