The 26-year-old, who returned to Paris this weekend to begin his final recovery phase from foot surgery, has been heavily linked with a move to the European champions.
Neymar has spent less than a year in the French capital, having left Barca for a world-record €222 million fee last August, but is reportedly less than satisfied with life at Parc des Princes.
Edmilson thinks his compatriot "left Barca in not a very good way" and a move to Madrid after the World Cup is perfectly possible, regardless of any remaining allegiance to the Catalans.
"I was surprised Neymar left Barca, but he and his team have their things," Edmilson told El Larguero . "I wouldn't be too surprised if, after the World Cup, Neymar signs for Madrid."
Barca host Madrid on Sunday in a game overshadowed by a spat over a pre-match guard of honour.
Zinedine Zidane's side have refused to honour Barca's La Liga title win with the gesture because the favour was not returned in the reverse fixture, which followed Madrid's triumph in the Club World Cup.
Edmilson played in Barca's 4-1 Clasico loss in May 2008, which was preceded by a guard of honour for Madrid, and the Brazilian feels it is a worthwhile gesture.
"It's not a humiliation," he said. "On the contrary, it's respect for a team who have had an awesome and very strong league season."
Sunday's game will be Andres Iniesta's final Clasico, with the midfielder set to leave Barca at the end of the season, and Edmilson was effusive in praise of his old team-mate.
"He is a fantastic player and person," he said. "La Liga will miss him. He's a person who has played all his life in one team, and in the Spanish national team, and he has made history.
"He's one of the most easy-going and talented people I know."