The striker left the club to join Fulham this summer after three years at St James's Park.
Mitrovic had helped Slavisa Jokanovic's side win promotion to the Premier League last season during a successful half-season loan.
The 24-year-old had found his opportunities limited at Newcastle under Benitez.
And Mitrovic has admitted that he was never "comfortable" playing for Benitez, though he insists they had a "good relationship".
"We just didn't suit each other," says Mitrovic, who has scored five Premier League goals for Fulham so far this season.
"I didn't suit his tactics, and I didn't really feel comfortable to play, so he couldn't get the best out of me.
"But it's nothing personal – just business.
"We had a good relationship and he is a good guy. Defensively, he's one of the best managers that I've worked with."
Mitrovic is enjoying the relative anonymity of living in London.
"It was really hard in Newcastle," Mitrovic told BBC Sport. "It was one city, one club. Everybody there was really crazy about Newcastle.
"Sometimes it is nice, but sometimes you want to be quiet and go out with your family. When you are not happy on the field, you just don't want to think about football, (you want to) have your space.
"In Newcastle, there is no chance."