Speaking to Entertainment Weekly, the country star revealed that he was impressed by Stevens, who was voted off the show alongside Andrew Garcia last week.
"I thought she was really good! She had a thing. When I watched, I couldn't stop watching her sing. I thought she had a great delivery, and I thought she was incredible. And I am sad to see her go," he said.
Hillary Scott added: "Keep going, Katie! I tried out for American Idol twice, and didn't get past the first round, if that gives anyone hope. Keep going!"
Lady Antebellum, who scooped three gongs at last night's ACM Awards, will perform on this week's Idol Gives Back, which airs Wednesday night at 8pm on Fox.