Aldean won Entertainer of the Year for the second year in a row, while Lambert took home Female Vocalist of the Year for the eighth consecutive year.
Aldean walked the red carpet with wife Brittany Kerr before performing his song "Any Ol' Barstool" during the awards show. The 40-year-old singer was nominated with such stars as Keith Urban, who performed "The Fighter" with Carrie Underwood.
Lambert, who dazzled on the red carpet with boyfriend Anderson East, sang an emotional rendition of her new song "Tin Man." The track hails from her sixth studio album, The Weight of These Wings, which won Album of the Year.
"I'm just glad to see females kicking [expletive] these days. I'm so proud to be part of that. So cheers to all of us dreaming!" the singer said in her acceptance speech.
Thomas Rhett, meanwhile, won Male Vocalist of the Year for the first time after debuting his new song "Craving You" with Maren Morris. The 27-year-old star attended the ceremony with his pregnant wife, Lauren Gregory Akins, and also took home Song of the Year for "Die a Happy Man."
"Everyone is this category are my idols," he said of Male Vocalist of the Year. "Everyone is this category shaped the artist that I am. I try to be the best singer that I can. Thank you so much to the ACM. This is the most amazing award I've ever received in my whole existence."
Other highlights included performances by superstar couple Tim McGraw and Faith Hill, and by Florida George Line and the Backstreet Boys. Florida Georgia Line won Single Record of the Year for "H.O.L.Y." and Vocal Event of the Year for "May We All" featuring McGraw.