Romario, who retired in 2008 and became America's sporting director in 2009, played for Brazil in two World Cups, scoring five goals to guide them to victory in 1994.
In 2009, he briefly came out of retirement to play 22 minutes for America, his late father's favourite team, in a match that crowned them champions of Rio de Janeiro's second division.
Romario's son Romarinho also plays for America.
In a post on his Instagram page on Tuesday, Romario said: "I'm not going to compete in the championship, but rather play a few games for the team of my heart and make another dream come true, playing alongside my son.
"What do you think?"
Rio de Janeiro's football federation confirmed Romario's registration as a player, adding that he will receive a minimum wage, which will be donated to the club.
Romario made more than 70 appearances for his country between 1987 and 2005, scoring 56 goals. He had four stints with Vasco da Gama and also played for Flamengo and Fluminense in Brazil, Barcelona, PSV Eindhoven and Valencia.
He claimed to have scored more than 1,000 goals in his career, but those statistics include strikes in youth level, unofficial and friendly matches.
After retiring from football, he became a senator and led congressional investigations into corruption in Brazilian football.
