The Belgium international won the league title under Mourinho in the 2014/15 season, when the former Inter Milan and Real manager was in charge at Stamford Bridge. The latter was shown the exit door in December 2015 after a disappointing run in the first half of the 2015/16 campaign.
Hazard's relationship with Mourinho was reportedly strained, especially after the 26-year-old struggled during his former manager's final months at the west London club. However, the Blues No 10 has brushed off those suggestions by admitting that he is open to the idea of playing under his ex-boss.
"It wouldn't bother me to play under Jose Mourinho again," Hazard told RTL, as quoted by the Daily Mail.
After being shown the exit door at Chelsea, Mourinho returned to management as he was appointed as Manchester United manager last summer. In his debut season at Old Trafford, the Portuguese tactician won the EFL Cup and the Europa League.
Meanwhile, Real have long been interested in signing Hazard from Chelsea. The former Lille man has also flirted with the idea of moving to the Spanish capital club after admitting it would be a "dream" to play under his idol Zinedine Zidane, who is the manager at the Santiago Bernabeu.
"Everyone knows the respect I have for the man. For the player he was and for the coach he is, he was my idol. Of course I don't know what will happen in my career in the future, but to play under him would be a dream," the forward explained.
Despite talking about the possibility of playing under Mourinho and Zidane in the future, Hazard has stressed that he happy at Chelsea "at this time."
"At this time, though, I'm happy at Chelsea. I still have a lot of things to do at Chelsea, and I'm focused on Chelsea," he stressed.