The singer fell into the bottom two along with Rob Kardashian and his professional partner Cheryl Burke following the combination of the judges' scores and viewer votes.
Phillips scored 21 out of a possible 30 points on Monday's show for her tango with partner Tony Dovolani to the theme from Mission Impossible on the ABC competition's Movie Week.
Judges Len Goodman, Carrie Ann Inaba and Bruno Tonioli each applauded her efforts but could not deny the poor performance which resulted from Phillips's inability to remember the choreography of the routine. Goodman had expressed disappointment at the musician's "lost" expression.
> Digital Spy recaps week 4 of 'Dancing with the Stars'
"I'm disappointed. I'm sad, but I have to take responsibility. I messed up and I have an amazing partner. I love you, Tony," Phillips said following her exit.
"Tony's amazing, he's been there for me 100% all the way and I'm very grateful to have been on the show and had the opportunity. Thank you to everyone for voting for me."
Dovolani added: "The first thing that crossed my mind [during last night's performance] was to try and take care of her because I saw the frightened look on her face. I wanted to calm her down, tell her it's okay and it happens to all of us. She listened to me, so that's cool."
Basketball player Ron Artest was the first celebrity to leave the competition along with professional partner Peta Murgatroyd, followed by Elisabetta Canalis and partner Val Chmerkovskiy. Kristin Cavallari and Mark Ballas left the competition last week.
Tonight's results show featured a performance by Raphael Saadiq, who covered James Brown's classic hit 'Soul Man', and Susan Boyle with a rendition of 'Unchained Melody' from her forthcoming album Someone to Watch Over Me.
Former Dancing with the Stars professional Julianne Hough also returned to the show for two special performances, including a number from her new film Footloose alongside co-star Kenny Wormald with music provided by Blake Shelton.
She also reunited with brother and fellow professional Derek Hough on the dancefloor for a spirited swing routine choreographed to 'Shake A Tail Feather'.
Dancing with the Stars airs Mondays and Tuesdays on ABC.