The event, which honors human rights defenders from around the world, took place at The Beverly Hilton Hotel in Beverly Hills, California.
The Law & Order: SVU star kept it simple yet chic in a stunning LBD that was cinched with a belt and a cute handbag as a fun accessory.
SVU creator Dick Wolf was also on hand for the important evening.
Allison, who also presented an award on Tuesday night, looked beautiful in a black pantsuit over a while top and some killer heels.
She brought along her beautiful niece Petra Janney who dazzled in an all-black ensemble.
Whose outfit did you prefer: Mariska or Allison's? Sound off in the comments.