Ms Harris said many of the retailers are giving the bags to customers for free if they make a minimum purchase. Or people can buy the bags - $3 for the small bag and $5 for the large bag.
She said some retailers were using the bags in creative ways, such as Central House Movers, who give out their contracts in Bull Bags.
Prime Minister Jacinda Ardern was given a Bull Bag when she stopped in Bulls on January 24, on her way to Ratana for the Ratana celebrations.
Ms Harris said she hoped the Bull Bag would make people think about how much plastic they use in the everyday life.
"Plastic is everywhere these days. We want to do something to reduce plastic bag use in Bulls.
"It's a baby step, but it is a step."