The two times FIFA Player of Year winner was arrested for entering Paraguay with a fake passport.
Having played in an in-house football tournament, ESPN say Ronaldinho is now doing woodwork with other inmates.
Paraguay footvolley player Fernando Lugo said the former Barcelona forward didn't stop smiling when visiting him in prison.
Meanwhile, he featured played with other inmates scoring five and assisting many other goals.
Ronaldinho was part of the Brazil team that won the FIFA World Cup in 2002 and also inspired Barcelona to win the UEFA Champions League in 2006.