Karli Webster is moving on to the next round of “The Voice” after winning her Battle on Monday night with a haunting rendition of the Cyndi Lauper classic, “Girls Just Want To Have Fun.”

The 20-year-old Canyon Country native joined dozens of friends, family and fans for a viewing party at a local restaurant, where she watched her duet with 16-year-old Addison Agen premiere on NBC.

Karli Webster during her Battle Round performance on “The Voice.” Courtesy of NBC, The Voice.

“Miley (Cyrus) choosing to stay with me proved to me once again that I need to believe in myself more, because she obviously believes in me,” Webster told KHTS at the party. “Her picking me just proved to me even more that she does know where she wants to go with me … and that is amazing that my childhood idol has a plan for me as an artist.”

Related: Karli Webster On ‘The Voice’: ‘I Want To Be Able To Make A Mark On This Show’ (VIDEO)

Webster described the moment Cyrus named her the winner of the Battle as “perfect,” recalling that it was such an evenly matched pairing that she and Agen had no idea who would win.

Cyrus said on the show it might be the hardest decision she’s ever had to make during her time as a coach on The Voice, and that in the end, she went with her heart.

“I think the best reason to pick someone is you’re genuinely a huge fan, and I’m a fan of Karli’s,” Cyrus explained. “She’s a type of artist that I would listen to in my everyday life.”

After being given the song choice “Girls Just Want To Have Fun” by her coach, Webster admitted she wasn’t sure how it would turn out.

“Listening to it was like, this song is not for me,” she said. “But me and Addison spent that whole night with a piano trying to work something out… Then moving forward, Miley just gave us more and more ideas that turned it into what it is now, and we are so proud of it.”

Karli Webster battles with Addison Agen. Courtesy of NBC, The Voice.

Harmonizing with Agen during the song came naturally to Webster, who noted her Battle partner’s deep, grounded voice complemented the higher-pitched, airy quality of her own voice perfectly.

Related: Karli Webster Of Santa Clarita Survives First Round Of ‘The Voice’ Blind Auditions

As of Tuesday afternoon, Webster and Agen’s version of “Girls Just Want To Have Fun” was at #36 on the iTunes charts and climbing.

“I feel like our voices were meant to be sung together, and Miley said that and so did her dad,” Webster said, referring to Billy Ray Cyrus’ role as an advisor for Team Miley in the Battles.

The girls’ close friendship before their pairing and leading up to their performance left Webster and Agen content with whatever decision Cyrus made, and both had high hopes that one of the other coaches would “steal” the remaining artist.

“We weren’t even looking at it like a battle, it was more like we just want this duet to be the best that it can possibly be,” Webster said. “Our ultimate goal was that one of us would get stolen, and that’s exactly what happened.”

When Coaches Adam Levine and Jennifer Hudson both pressed their buttons to steal Agen, Webster recalled “basically falling down the stairs crying” because she was so excited and overwhelmed, which she noted “thankfully” didn’t make it into the episode.

Karli Webster watches her Battle air on NBC at a viewing party. Photo by KHTS.

With friends, family and fans surrounding her Monday night, Webster was able to relive the entire experience for the first time, from her rehearsals with the Cyrus father-daughter duo to the events following her winning performance.

“This is a huge moment for me,” she said. “It’s so fun to watch even (the rehearsals) because I was just so blacked out even then, because I was so amazed to be standing in front of Miley and Billy Ray Cyrus… It was very surreal then, but it makes it real now.”

Next for Webster on the show is Team Miley’s Knockout Round, where the artists get to choose their own songs to perform individually in a matchup against another artist from their team — with only one winner moving on.

“That’s the moment where we really have to decide what kind of artist we want to be,” Webster said. “Being so influenced by older music, but also kind of wanting to reinvent it, I had a hard time deciding if I wanted to do an older song or a newer song. But with Miley’s help, I feel very confident in that performance and I’m excited to watch it.”

Follow Karli Webster’s journey as the show progresses Mondays and Tuesdays at 8 p.m. on NBC.

More photos from Karli Webster’s viewing party Monday night, by KHTS: