The K-pop group also sent a sweet message to Cardi B's daughter, Kulture.
BTS has been living it up while in Los Angeles.
The K-pop group arrived in color-coordinated Louis Vuitton looks at the 2021 American Music Awards on Sunday, where they told ET's Cassie DiLaura all about their night out with Lizzo at the Harry Styles' concert over the weekend.
"It was fun, very fun," J-Hope shared, before Jungkook added that his shirt was soaked in sweat from dancing so much.
When asked if they got a chance to chat with Lizzo about collaborating on a song together, Jimin noted that it was so loud they couldn't really chat.
"We shared phone numbers," J-Hope added, with RM agreeing that they are "so open" to working on a song together. "She's so fire."
Last week, Cardi B told ET that her 3-year-old daughter, Kulture, is a huge BTS fan. The seven singers couldn't help but send little Kulture a sweet message.
"Kulture, you know what's up!" RM said.
V, Suga, Jin, Jungkook, RM, Jimin, and J-Hope are up for three AMAs. They will also be performing "My Universe" with Coldplay and "Butter." Megan Thee Stallion was supposed to join the group for the remix but had to drop out last minute. That didn't stop BTS from being in good spirits, as RM said, "We've been waiting for this for so, so long time," about performing live.
"It's like a dream," Suga added.
"We actually dreamed of this dream, so it's crazy!" RM agreed. "We're just here to have a good time. With the ARMYs, with actual people, not AIs!
Additionally, ET also spoke on the red carpet with Why Don't We, who shared that they were so "excited" for BTS' performance. Watch the video below to hear what they said.