Farinas was released after being taken to a hospital for chest pains, the BBC reported.
Alicia Hernandez, his mother, said her son's latest arrest came as he and about 10 other dissidents were laying flowers at a monument to Cuban independence leader Jose Marti.
"His health is delicate, and doctors have recommended rest," Hernandez said.
Farinas nearly died following a 134-day hunger strike in 2010.
Farinas is a psychologist and writer and was awarded the Sakharov Prize for Freedom of Thought by the European Union in December, but prevented from leaving Cuba to accept the award, CNN reported.
He has been jailed for more than 11 years on a variety of charges and has staged more than 20 hunger strikes, reports said.
Farinas was held for about six hours Wednesday when he and a group of at least 17 other people tried to stop the eviction of a woman and her two children.
Thursday he was arrested with another group of people near the home of political dissident Idania Yanez Contreras. He was held overnight.