The duo lost out in the sing-off against Kye Sones after both acts received the fewest amount of public votes this weekend.
MK1 chose to sing their own interpretation of The Script's 'The Man Who Can't Be Moved', while Sones performed 'I Can't Make You Love Me'. However, MK1 were eliminated after the judges voted to take the decision to Deadlock for the third consecutive week.
Mentors Gary Barlow and Louis Walsh both opted to save their own acts, with Barlow claiming he thought Sones's performance was one of the strongest sing-off performances he had seen in the competition.
The next judge to vote was Nicole Scherzinger, who chose to send home MK1 based on the performances she had just witnessed. Tulisa said she had to stick by her "urban roots" and chose to send home Kye Sones as a result. With two votes each, the result was taken out of the judges hands and reverted to this week's public vote.
It was then revealed that MK1 had received the fewest amount of public votes, and would be leaving the competition.
Mentor Louis Walsh admitted he was "sad" to see the duo leave the competition but hopes that "someone will give them a record deal".
He continued: "Charlie and Sim are such good fun. I thought I would have got a few more weeks of them."
However, he insisted that their exit was not as a result of having the wrong mentor.
Asked on The Xtra Factor how he felt after the elimination, MK1's Sim said: "We felt we gave everything in that performance last night and we kind of were confident it could have been enough."
Fellow member Charlie Rhodes then thanked fans for voting for them and described their time on the show as the "best experience".
When asked by Xtra Factor hosts Caroline Flack and Olly Murs how she felt about MK1's exit, Tulisa said that she was "really emotional" to see the urban act leave the show.
She said: "The second I saw them, they reminded me of N-Dubz."
She admitted the duo's relationship reminded her of her relationship with fellow N-Dubz member Dappy.
The X Factor continues next Saturday at 8.20pm on ITV1.
Photo gallery - The X Factor Club Classics results show:
Copyright: Ken McKay/Thames/Rex Features