The US `X Factor` judge will front the annual Fox awards show on July 22, which sees her nominated for four accolades including two music gongs for hit `Give Your Heart a Break`.
Demi is up for Choice Summer Song and Choice Love Song in the music category, and she is also in line for the Female Choice Summer Music Star prize in which she will take on Katy Perry, Rihanna, Jennifer Lopez and Carly Rae Jepsen, who will perform at the ceremony.
As well as the `Call Me Maybe` hitmaker, Justin Bieber - who faces off against Demi for the Choice Twit award - Flo Rida and No Doubt will also take to the stage for the event, which is set to include an appearance by `So You Think You Can Dance` host Cat Deeley.
Demi`s appointment means she will have a busy summer presenting the ceremony, performing on her current summer North American tour, which concludes on September 1, and judging US `X Factor`.
The 19-year-old brunette recently admitted she occasionally feels "bad" about giving negative comments to hopeless wannabes on the talent show.
She said: "It`s really hard for me to smile if they`re performing and they`re horrible. I have to be super super honest and sometimes I feel bad about it."