Dressed in blue jeans, a denim jacket and a New York Yankees cap, Hill sat on a stool and strummed an acoustic guitar Saturday night.
"I used to get dressed for y'all but I don't do that no more," Hill joked as she began her set. "It's a new day."
The 26-year-old Grammy winner sang all new songs, some of which don't even have titles yet.
Later, she spoke seriously about her faith and shunning the trappings of fame, and several fans in the audience shed tears with her.
"I'm a mess but God is dealing with me every day," she said. "That's what all these songs are about: problem, cause and solution."
Hill's "Unplugged" appearance is scheduled to air on MTV2 in the late fall, and will rerun on MTV afterward.