Lambert, who'll perform with her band the Pistol Annies, will also join fellow nominee Jason Aldean on stage. Both Lambert and Aldean are nominated for Single of the Year and Musical Event of the Year for their song "Drowns the Whiskey."
The artists join previously announced performers Kacey Musgraves, Pistol Annies, Thomas Rhett, Dierks Bentley, Brothers Osborne and Florida Georgia Line, Bebe Rexha, Keith Urban, Carrie Underwood, Kelsea Ballerini, Luke Bryan, Kenny Chesney, Dan + Shay and Old Dominion.
Many of the performers are nominated for CMA awards.
Lambert is nominated for Female Vocalist of the Year alongside Kelsea Ballerini, Maren Morris, Kacey Musgraves and Carrie Underwood.
Aldean is nominated for Entertainer of the Year, facing off against Luke Bryan, Kenny Chesney, Chris Stapleton and Keith Urban.
Midland, Young and Combs are all nominated in the New Artist of the Year category. Midland is also up for Vocal Group of the Year.
Chris Stapleton leads this year's nominations with seven nods. The "Tennessee Whiskey" singer is nominated for Entertainer of the Year, Male Vocalist of the Year, Single of the Year and Song of the Year (for "Broken Halos) and Album of the Year (for From A Room: Vol 2).
The 2018 CMA Awards, airing Nov. 14 on ABC, will be hosted by Underwood and Brad Paisley, who are celebrating their 11th consecutive year as co-hosts.