Blake Shelton pitted the country singers against each other for a battle round performance of 'Free Fallin'' after they had received guidance from his special mentors Kelly Clarkson and Miranda Lambert.
Watch RaeLynn and Adley's battle below:
Christina Aguilera opened the commentary by saying both singers had brought their own style to the song but she'd give the edge to Adley because she had more confidence, although she gave props to 17-year-old RaeLynn for having the guts to get up on the stage.
Cee Lo agreed that RaeLynn was "adorable" and said she had time to work on her vocal, but he thought Adley's experience was needed to win the competition so he went with her.
Adam Levine, however, chose RaeLynn as his winner because she gave a more unique performance, although he thought Adley did out power RaeLynn at points.
Before announcing his final decision, Blake said: "As a country artist we tell stories. I already know you're both great singers so I found myself trying to figure out which one has the ability to make me believe what they are singing. You both did a good job of that but one of you did a better job..."
That person was RaeLynn, who advanced to the next stage.
Speaking to social media correspondent Christina Milian backstage, she said: "It was a tough battle. I didn't know who they would choose. I love Adley and it was hard for me; she's like my big sister.
"Everybody here is an awesome artist so to see anybody go home is ridiculous because everyone is so good."
As for the future, Adley told Christina that she'd continue to pursue her dreams.
"This torch has just been lit in my life and once you experience something like this you can't quit!" she said. "When the music is in you it doesn't want to go away."
The Voice airs Monday nights at 8/7c on NBC
Watch Adley and RaeLynn talking to Christina Milian below:
Browse a gallery of pictures from the first battle round below: