WPP confirmed the World Cup winner is to take a job placement at the group - the world's biggest advertising and communications firm - and will work closely with chief executive Sir Martin to learn the tricks of the trade.
The pair have already worked together, with Ronaldo running sports marketing agency 9ine in Brazil for the past two years, which is a collaboration between the football hero and WPP.
He has also been helping the group on the upcoming World Cup and Olympics, which will be hosted by Brazil in 2014 and 2016 respectively.
Ronaldo, 36, told Brazilian newspaper Meio e Mensagem: "Learning from Martin Sorrell will be perfect.
"I won't leave him alone. I'll be asking him questions the whole day, just like a striker. He's going to have to tell me everything."
He won the World Cup in 2002 for his country, scoring two goals in the final, and was also named Fifa world player of the year three times.
It is believed his placement with WPP will last for at least two years, during which time he is reportedly expected to spend up to five months in the UK.
Ronaldo set up his agency 9ine based in Sao Paulo with a mission to exploit opportunities surrounding sports in Brazil through branded events, public relations and marketing.
WPP has a growing arm in Latin America, including around 6,000 employees in Brazil.
The wider group has around 158,000 full-time staff and annual profits of £1 billion.
It owns companies including public relations firm Ogilvy, communications agency RLM Finsbury and market research firm Kantar Worldpanel.