The `Diamond Rings` hitmaker personally congratulated Leah Newcombe from Hertfordshire, southern England, after her rhyme `Misfits` won the `2010 Def Jam Rapstar: Rhyme Master UK` competition.
Chipmunk said: "There was a lot of great talent that came through from all over the UK and I was blown away by how good some of the rhymes were.
"But Leah really stood out with an incredible heartfelt lyric about fitting in at school - so mature for only 13 years old."
The competition, run in conjunction with the UK`s National Literacy Trust, saw entrants rap over a beat or submit a written text, and was set up in conjunction with schools to help children understand the importance of vocabulary, rhythm and rhyme in writing.
Leah, who has since turned 14, said: "I worked on it for two days. Some of it contains things that I was feeling at the time. I really enjoy English at school and would love to do this as a job when I leave. I much rather write than perform, but I wouldn`t mind if Chipmunk wanted to rap my lyrics."
Meanwhile budding rappers of any age can enter record label Def Jam`s search for a rap star - which will see one person win a record deal with label Atlantic records - through their `Def Jam RapStar` computer game.
The game features a freestyle mode where entrants can record their own verses and upload them to the www.defjamrapstar.com, where the online community will then rate them, and after regional freestyle rapping heats, a winner will be crowned and given the deal.
The contest is endorsed by US rapper Flo Rida, who said: "I definitely see an artist coming out of the game. The ones who are going to make it are the ones who give it 200 per cent in every aspect, performance, clever with your lyrics and rhyme pattern as well as your whole swag."
Entrants can upload their tracks from January 1 next year.