The DR Congo defender was a key part of Benitez's plans at the end of last season, starting the last nine Premier League games.
The 21-year-old impressed after his summer move from Anderlecht, but was unable to stop Newcastle from slipping into the Championship.
He has since been linked with a move to Italian side Fiorentina, but he has intimated he is prepared to stay at St James's Park after Benitez committed his future to the club.
"On a personal note, it's really good to have worked with him," Mbemba told the club's official website.. "I've worked with a lot of coaches over the last few years, and Rafa is one of the best.
"He's absolutely fantastic. He's a Champions League winner, he's managed Real Madrid, he's managed Liverpool and personally, I think he's really helped me improve as a player.
"It's really important. The coach, when you look at him, is like a teacher - he watches everyone, all of the players and he gives you the confidence to go out there and do what you do best, so I would like to thank him a lot for that.
"I played a lot of games last season. It was my first season here and I played 30-something games and that was really fantastic for me."