The Canadian-born actress and animal rights activist is among several celebrities who are taking part in an ad campaign by People for the Ethical Treatment of Animals.
Anderson visited the Ontario provincial legislature on Friday to introduce the new ads that will also feature singers Sarah McLachlan and Kelly Osborne and celebrity blogger Perez Hilton.
Anderson told the TV show "Canada AM" that she's "angry" about the seal hunt, describing it as "barbaric and cruel" and "an embarrassment" to her native country.
The indigenous Inuit community says the seal hunt provides crucial jobs and food for villagers in isolated northern communities in Canada.
Canada's East Coast seal hunt is the largest in the world, killing an average of 300,000 harp seals annually.