The 50-year-old signed a four-year deal to become Blues boss for a second time on Monday, two days after overseeing his final game in charge of Real Madrid.
And Ivanović, who joined Chelsea from Lokomotiv Moscow in 2008 just a few months after Mourinho left the club for the first time, is relishing the prospect of working under the former Porto and Inter Milan boss.
“I am really happy because it is a pleasure to work with one of the best managers in the world,” said Ivanović.
“I know it is going to be hard and very tough, but I am looking forward to that.
“I think he is the best we could have expected for Chelsea and everyone who loves the club. Fans will be excited to see him.”