The 10-minute Flash Vote will take place at the end of each Saturday live show and will allow fans a short chance to vote for the acts that they want to save from the drop.
After all the contestants have performed, the voting lines will open and the public can select their favourite performer. When the phone lines close, the act with the lowest number of votes will be told that they face Sunday night's sing-off.
Voting lines will reopen on Sunday night's show, where the second contestant to face the sing-off will be revealed.
The new twist has replaced the unpopular decision to have voting open throughout the Saturday night show last year, which many critics described as a cynical attempt to make more money from phone votes.
The X Factor Judges' Houses round takes place this weekend and the Final 12 acts will be unveiled on Sunday (October 6).
Gary Barlow is looking after the Groups this year, Louis Walsh will mentor the Boys, Nicole Scherzinger has the Girls and Sharon Osbourne takes control of the Overs.