Lovato will help get the ball rolling on the big night with a performance of her hit "Give Your Heart a Break" during the hour-long VMA pre-show, which will air live on September 6 from 7 p.m. to 8 p.m. ET/PT. Demi will warm up the VMA crowd prior to the start of the main attraction, which is set to air live from the Staples Center in Los Angeles beginning at 8 p.m. ET/PT.
"I'm so excited to perform at the VMA preshow. I can't believe it!" said Lovato.
She won't be alone, of course, as the warm-up show's soundtrack will be provided by none other than chart-topping EDM artist, DJ and mega-producer Calvin Harris.
Nominated in the Best Electronic Dance Music Video category, Harris will warm up the VMA crowd for an hour prior to the start of the main attraction.
As a part of MTV's "2012 Video Music Awards Pre-Show," MTV News' Sway Calloway, Jim Cantiello, James Montgomery and Christina Garibaldi will take viewers live to the vertical red carpet, behind the scenes and backstage with some of music's hottest stars. Also on the carpet, British TV host and fashion expert Louise Roe will return as MTV's international guest correspondent for the second year in a row.
Leading up to the pre-show, MTV will air a "Jersey Shore Look Back Special" at 6 p.m. ET/PT, featuring clips from past episodes, commentary from the cast and never-before-seen footage in preparation for the upcoming sixth season of "Jersey Shore" in October. During the special, the cast will break in with live hits from the red carpet with their reactions, remarks and messages for fans. The pre-show will also feature the announcement of the all-new "Most Share-Worthy Video" award, presented by Bing.
Lovato will get the party started for a sizzling roster of main-show performers that already includes the VMA debut of One Direction, as well as spots from Taylor Swift, Green Day and Pink. Five-time VMA nominee Rihanna joined the heat on Monday, along with the VMA performance debut of talked-about Odd Future crooner Frank Ocean.
Rihanna is tied with Drake for the night's most nominations, including two bids for Video of the Year.
Among the presenters also confirmed for the show are the Wanted, Andy Samberg, Rashida Jones, 2 Chainz, Ke$ha Miley Cyrus, Wiz Khalifa, Mac Miller and the "Fierce Five," the U.S. Women's Olympics Gymnastics Team that won the team gold medal at the 2012 Olympic Games. The show will be hosted by comedian Kevin Hart and will also feature a performance from Alicia Keys.