Aldo tipped the scales at 145 pounds, while Edgar weighed in at 144.
The UFC 156: Aldo vs. Edgar card airs live on pay-per-view at 10 p.m. ET.
Besides a featherweight title bout between Edgar and Aldo, UFC 156 features a heavyweight scrap pairing former Strikeforce champion Alistair Overeem (264) with Antonio Silva (262), a welterweight bout pitting the American Kickboxing Academy’s Jon Fitch (171) against Demian Maia (170) and a flyweight bout pairing Team Alpha Male’s Joseph Benavidez (126) with Ian McCall (125).
UFC 156 co-headliners Rashad Evans (206) and Antonio Rogerio Nogueira (206), also met their contracted weight requirements without incident at the UFC 156 official weigh-in.
There's a lot on the line on the UFC 156 main card.
A strong performance by Evans may put him in line for a title shot against UFC middleweight champ Anderson Silva, and Overeem will likely fight UFC heavyweight champ Cain Velasquez with a victory over Silva.
FX will air four UFC 156 preliminary bouts; Gleison Tibau (155) vs. Evan Dunham (155), Tyron Woodley (170) vs. Jay Hieron (168), Jacob Volkmann (156) vs. Bobby Green (155) and Yves Edwards (155) vs. Isaac Vallie-Flagg (156).
The two remaining UFC 156 undercard matches will stream at 6:35 ET on the promotion's official Facebook page, as Chico Camus (134) locks horns with Dustin Kimura, and Edwin Figueroa (*136) fights Francisco Rivera (*135.5).
Kimura failed to get down to 136 pounds, as he weighed in at 139 pounds. As a result, he must forfeit 20 percent of his purse.