The 20-year-old singer and 32-year-old entertainer were joined at the event by fellow judge Paulina Rubio.
Stay tuned later in the day for pics from day two of the auditions!
The X Factor season three will kick off on September 11 on FOX – be sure to tune in!
FYI: Demi is wearing an Isabel Marant dress and Schutz shoes. Kelly is wearing a Wayne shirt and skirt, Christian Louboutin boots, and King Jewelers diamonds. Paulina is wearing a Zac Posen dress, Bimba & Lola gloves, House of Harlow sunglasses, and a Luis Morais bracelet.