Salespeople and doorknockers who ignore stickers could now face hefty fines and have sales deals torn up in court.
Consumer NZ said new laws taking effect today were a triumph over "pushy salespeople hounding householders to buy products they don't want or need".
Changes to the Fair Trading Act were the product of an eight-year campaign against pestering salespeople.
"You don't need a sticker to benefit from these new consumer protections," Consumer NZ added.
"If you tell a seller to stay away from your house, they must do as they're told for two years."