Corinthians, who won 2-0, said in a statement that the Argentinian fan, who the club did not name, was reported by the home supporters to the municipal police at Sao Paulo's Neo Quimica Arena for making racist monkey gestures at them.
The alleged perpetrator was taken to the civil police department where he was accused of making a racist slur, a punishment that can carry a prison sentence up to three years, as well as a fine.
The Argentinian supporter was then released by police after a 3 million reais ($607) bail was paid by the Argentinian Consulate.
Both Boca and Corinthians condemned the racist incident with the former confirming it will consider what measures and potential sanctions will be taken against that individual at their next executive committee meeting.
Sao Paulo's police, meanwhile, confirmed they are investigating the author of an Instagram post that mocked the arrest of the Boca fan in Brazil.
The controversial post, appearing in the account name of Nicolas Garay, shows two Boca fans smiling with one of them giving a thumbs-up accompanied by the phrase "nothing happened here" with a monkey emoji.
One of the men in the photograph resembles the Boca fan that was arrested in Sao Paulo.
"We are communicating with our intelligence unit to obtain the registration data of this Instagram page and we will register the case as a racial slur," Cesar Saad, a deputy of the Sao Paulo police Crimes of Sport Intolerance unit said.
"We will inform CONMEBOL so that this other fan, Nicolas Garay, also suffers the appropriate measures from CONMEBOL and Boca Juniors."