ET caught up with the 17-year-old singer in Los Angeles on Thursday at her album immersive pop-up experiencepresented by Spotify. During our chat, she opened up about her love for the heartthrob and shared a story about the time he direct messaged her on Instagram.
Discussing all the celebrity fans Eilish has ramped up ever since her debut single, "Ocean Eyes," went viral in 2016, ET's Katie Krause asked the singer if anyone's been "sliding into those DMs" yet.
"I mean, Justin Bieber did!" Eilish responded, adding that fans will have to wait to see what he sent her when he finally followed her back on the social media platform. "One day you'll find out, but that s**t was crazy."
"The first thing he sent was a screenshot of a DM I sent him in 2014," she teased. "You know how when you follow somebody, you can see everything they DM'd you in the past? It, like, it felt good and it felt bad at the same time."
Though Eilish hasn't had the opportunity to meet Bieber in person (yet!), she's been a fan of his for years now. "It started when I was, like, 12, I believe," she confessed, adding that she totally had "big a**" posters of him plastered all over her bedroom walls.
"He's amazing," she gushed. "He's so sweet and, like, I feel -- just, honestly, I feel for him, man. He's been through a lot, dude."
Like Bieber, Eilish has found her own success in the music industry at such a young age. She began writing original songs at the age of 11, and released her first EP, Don't Smile at Me, in August 2017, when she was 15 years old.
Now, Eilish is preparing for the next big step, with the release of her debut studio album, When We All Fall Asleep, Where Do We Go? Although it was just released on Friday, the singer-songwriter has already been slashing Spotify and Apple Music Records. Asked if she's ready for this next level of stardom, Eilish adorably exclaimed, "No!"
"No, honestly, I think, like... I feel like I am," she clarified. "I feel like I always have been [ready] a little bit, without really realizing it."
"That girl is the king!" she marveled. "She's the king. For sure. I don't know, it's really [sick] to see how things are changing and how people [are] kind of, like, understanding that [us girls] are all just doing our thing."
"I'm just hoping for the best," Eilish added of her own path. "I'm just trying to enjoy it and not complain. 'Cause what is there to complain about?"
For a peek inside Spotify's Billie Eilish Experience -- and to see her amazing reaction at the moment her album dropped -- check out the video below.