The girl group - Jesy Nelson, Perrie Edwards, Leigh-Anne Pinnock and Jade Thirlwall - have racked up over 51% of the vote in a DS poll of the final three acts.
Nearly 30,000 fans have voted in the survey, which places Amelia Lily as runner-up ahead of Gary Barlow's Marcus Collins.
Little Mix have been triumphing in DS polls since the halfway stage in the live shows, overtaking early favourites Collins and Janet Devlin.
The girlband, who are now the bookmakers' favourites, would be the first group to ever win The X Factor if they triumphed.
Tulisa Contostavlos will duet with her group on Saturday's Wembley Arena finale, while Kelly Rowland will partner with Lily and Barlow will perform with Collins.
The X Factor final kicks off on Saturday (December 10) at 8pm on ITV1. Marcus Collins, Amelia Lily and Little Mix are fighting it out for the chance to land a Syco record contract and a Christmas single.
> 'X Factor': Amelia, Marcus, Little Mix to duet with mentors at final
Watch the X Factor finalists' press conference below: