The country star was the first coach to press his button during her blind audition performance of 'Maybe I'm Amazed', followed by Christina Aguilera and Cee Lo Green, who turned around at the same time.
Shelton told her: "That is the voice I've been sitting here waiting to hear and you're the type of singer that makes me excited about what I do and your voice makes me want to push myself to be a better singer."
He also jokingly pointed out that Dia Frampton, one of his team members from last season, is currently touring with him.
Speaking to social media correspondent Christina Milian backstage, Unga said: "Blake said all the right things and [I saw] the way he treated his team last year.
"The fact I had somebody turn around before I got to the big chorus made me feel so much more comfortable, like now I could just sing it without thinking, 'Turn around!'"
She added: "I was really torn about what to do. I'd love to work with a vocalist like Christina, but I had to go with my gut on this one and I'm beyond excited."
The Voice airs Mondays at 8/7c on NBC.
> The Voice blind auditions part 3 - live blog
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Watch Jordis Unga talking to Christina Milian below:
Browse photos from the blind auditions below: