Roberts (11-1) will be looking to make it three straight wins in the octagon after winning back-to-back victories over Forrest Petz and Mike Guymon. Soto meanwhile captured his first UFC victory in August, defeating Nick Osipczak in a decision. That win improved his career record to 8-1, with his only loss coming via disqualification.
The bout is scheduled to take place as part of the UFC 125 undercard.
UFC 125 takes place on Jan. 1 at the MGM Grand Garden Arena in Las Vegas and is highlighted by two title fights.
In the main event, lightweight champion Frankie Edgar defends his belt in a rematch with Gray Maynard, while featherweight champ Jose Aldo defends his belt in a UFC cage for the first time in a fight against Josh Grispi.