A five-cent fee on plastic and paper bags is now city law.
Mayor de Blasio signed the measure along with several other bills Tuesday.
Beginning in October, shoppers will pay a nickel for every plastic or paper bag they get from most stores.
Restaurants, liquor stores, food pantries will be exempt from the fee, and you won't pay for those small paper medicine bags at pharmacies.
Manhattan Councilwoman Margaret Chin co-sponsored the bill, which was approved by the Council in a close vote last week.
"I understand that change is difficult. However, if we are to make a significant dent in this gigantic amount of waste polluting our environment, all of us need to do our part," Chin said.
Supporters of the law hope it will encourage shoppers to bring reusable bags with them to the store.
Critics have suggested the fee is just another tax that will hurt low-income New Yorkers.