Jonas Brothes introduce their little brother Frankie

The Jonas Brothers have proudly introduced their younger brother to the world at the premiere of Camp Rock 2: The Final Jam.

Nine-year-old Frankie hit the red carpet in New York as one of the new cast members for the sequel to the lucrative Disney special.

“I was just so happy to hear that they wanted me in the movie, I was like ‘yes, yes, yes!’ I was very happy,” he excitedly explained at the premiere.

The young star revealed he was the most mature when it came to working with brothers Kevin, Joe and Nick on the shoot.

“Sometimes they would be having fun and I’d be like ‘guys – focus,'” he insisted.

With a recurring role on the family’s Disney sitcom Jonas LA, Frankie said he was enjoying establishing himself as a performer in his own right.

“I would like to pursue my acting career but also do a little singing in the middle. I play a little drums and the littlest bit of guitar,” he revealed.

But the youngest Jonas said he wasn’t quite ready for his own screaming fans just yet.

“I don’t think so, but I’ve been practising, ‘here’s a picture,'” he joked, miming giving out photos to fans.

Frankie said he hasn’t quite mastered the art of signing autographs either.

“I’m not the greatest because I push the pencil so hard, so I just put my name in print,” he said.

Camp Rock 2: The Final Jam airs on September 17 at 6.30pm on Disney Channel.