Raphael Honigstein revealed on Twitter this afternoon that he has received the confirmation from two separate sources.
"Mourinho to Chelsea buzz getting louder. two very different people with CFC connections insist it's a done deal," he wrote on Twitter. "One source an agent, the other a commercial partner of the club."
Mourinho, who is currently in charge of Real Madrid, left the Blues in 2007 following a three-year stint at Stamford Bridge.