"It's pretty rad, I can't believe it. It's so rewarding," Reinhart told MTV News following her performance. "I'm feeling so honored to be a part of it."
Reinhart was among the first acts to perform on opening day of the festival, wowing hundreds of fans with songs from her debut album, Listen Up!, which was released in May. Yet, it was the people that joined Reinhart onstage that made the experience all the more memorable.
"Not only did I have an amazing band that I've barely played with behind me, but my mom and sister doing backup vocals, my dad on guitar, just such an incredible feeling," she said.
Reinhart, who hails from Wheeling, Illinois, a suburb of Chicago, explained that this was her first time at Lollapalooza but was not bothered by nerves playing in front of her hometown crowd.
"I think I was more nervous every day leading up to this point and I got here and it kind of all went away. I let loose," Reinhart said. "I've had a little bit of experience with that and the big crowds and live performing like this is what I really love. It's my passion. I let loose and had a ball with it."
The Lolla crowd also heard something new from the former "Idol" star: she busted out her rap skills. B.o.B, who is featured on "Oh My!" from her album, wasn't able to hit the stage, so Reinhart took it upon herself to rap his part.
"I was just like, 'Oh, I think I got it.' I did it a couple of times. I listened to it enough that I knew it, and my adrenaline was skyrocketing," Reinhart said. "So it came kind of naturally."
Next up for Reinhart: She is hitting the road in the fall and is hoping to release "Oh My!" as the second single off her album. If she gets her wish, the singer already has the perfect idea for the video.
"I'm already jotting down ideas for that video. I've been doing it since Day One so I'm really excited to film that one," Reinhart said. "I want it to be really really kind of New Orleans authentic vibing crazy cool party club. Something crazy cool."
MTV News is at Lollapalooza slathering on the sunscreen! Stick with us for the best festival coverage, as we bring you up-to-the-minute access to the shows, performers and more.