Despite his agent's statements that Gerson will be training at Barcelona before the start of the new season, the young midfielder opted for a move to Roma.
In an interview with Mundo Deportivo in 2015, Gerson's father and agent said that a deal with Barca was all but done.
"Gerson will stay here at Fluminense and, in January, will play at Barcelona," Marcos Antonio da Silva said.
Rumours that the Giallorossi would be the team to land the Brazil Under-20 international proved to be true, however, and he was unveiled to the press on Saturday.
"I am happy to be here and wear this jersey with great pride. I will do my best," Gerson told reporters. "I chose Roma because they are a great team. It was the best choice for me.
"I would love to be remembered like many fellow Brazilians at Roma. Now I have to prove my worth on the field. Paulo Roberto Falcao is a legend, but I never got to see him play.
"We want to go all the way and win titles. I thank [director of sport Walter] Sabatini, who did everything to bring me here."