Sao Paulo governor Geraldo Alckmin named the ex-player to his state committee coordinating the football tournament in a ceremony in a Sao Paulo stadium.
He also awarded Ronaldo, 34, a medal in honour of his sporting achievements and legacy.
"It's an honour to help the government of Sao Paulo to put on the best World Cup of all time," Ronaldo said.
The three-time FIFA World Player of the Year, whose goalscoring genius led Brazil to the 2002 World Cup title, confirmed his retirement on Monday in a tearful media conference.
He said he was forced to halt his career because his body was no longer up to the demands he was putting on it.
The striker, who played for Barcelona, Inter Milan, Real Madrid and AC Milan, but who appeared only sporadically for Sao Paulo side Corinthians since returning from Italy in 2009, was plagued with injuries for much of his career.
He has said he hoped to wear the national Brazil jersey one more time in a farewell match "to bring together players who were with me and appear in front of a public who loved and helped me."
Ronaldo won the World Cup with Brazil in 2002 and became the leading scorer in World Cup finals tournaments when he scored his 15th goal at the 2006 tournament in Germany.
He was twice named European Footballer of the Year, in 1997 and 2002, and finished his international career with 62 goals in 97 appearances.