Cadena Ser say the 41-year-old is set to become the club’s majority shareholder and president.
The takeover could be ratified in the next two to three weeks and would reportedly settle the club’s debts of £22.7m.
The current president Carlos Suarez would remain in charge of managing the day-to-day business of the club, according to Cadena Ser.
Ronaldo is one of the greats of world football and won the Golden Boot when Brazil lifted the World Cup in 2002, having previously helped them to the final in 1998.
He was named FIFA World Player of the Year in 1996, 1997 and 2002.