The fights are on ESPN and stream on ESPN+, with the main card beginning at 10 p.m. ET and the prelims at 7 p.m.
Font (19-4) has won four fights in a row, most recently a unanimous decision over former champion Cody Garbrandt in May. Font is No. 5 in the ESPN men's bantamweight rankings.
Aldo (30-7), a former featherweight champ in the UFC and WEC, has won two straight after dropping three in a row, including a fight for the 135-pound title last year. He is ranked sixth by ESPN.
How to watch the fights
Don't have ESPN? Get instant access.
Stream the fights on ESPN+. Don't have ESPN+? Get it here.
There's also FightCenter, which offers live updates for every UFC card.
Saturday's fight card
ESPN/ESPN+, 10 p.m. ET
Men's bantamweight: Rob Font vs. Jose Aldo
Lightweight: Brad Riddell vs. Rafael Fiziev
Lightweight: Clay Guida vs. Leonardo Santos
Light heavyweight: Jimmy Crute vs. Jamahal Hill
Middleweight: Brendan Allen vs. Chris Curtis
Welterweight: Bryan Barberena vs. Darian Weeks
ESPN/ESPN+, 7 p.m. ET
Middleweight: Maki Pitolo vs. Dusko Todorovic
Welterweight: Jake Matthews vs. Jeremiah Wells
Men's flyweight: Manel Kape vs. Zhalgas Zhumagulov
Strawweight: Cheyanne Vlismas vs. Mallory Martin
Light heavyweight: Alonzo Menifield vs. William Knight
Lightweight: Claudio Puelles vs. Chris Gruetzemacher
Heavyweight: Jared Vanderaa vs. Azamat Murzakanov
Welterweight: Alex Morono vs. Mickey Gall
Men's bantamweight: Louis Smolka vs. Vince Morales