Watch Kelly Clarkson Perform Somber 'Hamilton' Ballad on 'The Voice'

Season 11 runner-up Billy Gilman joined singer for "It's Quiet Uptown" during finale episode, backed by string quartet

Kelly Clarkson and 'The Voice' runner-up Billy Gilman performed a duet of 'Hamilton' ballad "It's Quiet Uptown" during the Season 11 finale.

Kelly Clarkson teamed with Voice runner-up Billy Gilman to perform a somber version of the Hamilton ballad "It's Quiet Uptown" during the Season 11 finale. Backed by an understated piano and string quartet, both singers showcased their dynamic vocal range, building from near-whispers to booming, belted notes.

The Season 11 Voice finale boasted an eclectic guest list of performers, including John Legend, Stevie Wonder and Ariana Grande, Bruno Mars, the Weeknd and Sting. The evening's heaviest moment was KISS' instrument-smashing medley of "Rock and Roll All Nite" and "Detroit Rock City" alongside Voice winner Sundance Head.

Clarkson recorded a more electronic-oriented version of "It's Quiet Uptown" for the recently released Hamilton mixtape. The album features covers of tracks from the hit Broadway musical, including contributions from Chance the Rapper, Jimmy Fallon, Usher, Queen Latifah, Sia, the Roots, Alicia Keys, Ja Rule, John Legend, Regina Spektor and Busta Rhymes.

In a November interview with People, the singer announced plans to release a new single in April, followed by her eighth album in June. She described the LP, a follow-up to 2015's EDM-oriented Piece By Piece, as "soulful urban pop" that branches away from her past work.

"It's very much my personality,” she said. "I think it's very much what people expected from me off of watching me on Idol. I sang all these Aretha [Franklin] things, I love Tina [Turner], I love Mariah [Carey], I love Whitney [Houston]. I think it's very much what people expected in the first place. I love all my stuff that I've done but this is the record that has been in me since junior high. And that music from when I was in junior high is now coming back [into style] – like our 15-year-old listens to R&B that I listened to in high school."