The pair found themselves in the bottom two of Team Jessie and Team Danny along with Toni Warne and Max Milner.
Jessie J's team saw Cassius Henry, Vince Kidd and Becky Hill voted through to the next round by the viewing public.
Meanwhile, David Julien, Bo Bruce and Aleks Josh were voted through for Danny O'Donoghue's team.
Jessie J told Toni Warne: "I feel like people haven't seen the best of you yet. Your vocal ability is so extreme. Your voice is timeless."
Turning to Ruth-Ann St, Luce, she said: "You're 18 and the things you can do with your voice, so many singers will dream to be able to do. But you do have issues with pitch. Your path is gleaming, this is not the end for you."
After Jessie J decided to keep Warne in the competition, St. Luce told host Holly Willoughby: "It's been a crazy rollercoaster on this show. I've learned so much from Jessie and all you guys. It's been life-changing and this is not the end of me."
Later, Danny O'Donoghue stated: "No-one from my team deserves to get knocked out".
He told Milner: "When I turned around and I was in a bidding war with will, I saw a lot of myself in you. You've shown so many sides of you throughout the course. It's been a pleasure being your mentor all this while."
Speaking to Berney, he added: "From day one we've always been a collaborative team, and that's what I love. This show is just showcasing what amazing people are out there. The way you did that mash-up, that's what the industry needs, people thinking in a unique way."
Once he chose Milner to stay over her, a tearful Berney said: "This has been the best year of my life, I've been on live TV. I know what I'm doing now in my life."
The Voice UK will continue next week when Team Tom Jones and Team will.i.am will perform live for the second time.
Two acts from each team will leave the competition on Sunday (May 13), while they will also perform a track with their mentors.
The next live show will air on Saturday (May 12) at 6.10pm on BBC One.