The Westland Milk Products Westgold butter broached the million milestone last month, a year after first hitting supermarket shelves.
Westland Milk head of marketing Charlotte Sullivan said 190,000 households, or one in 10 New Zealand homes, had purchased the product in the past year.
In May, both the unsalted and salted butter blocks received bronze awards at the New Zealand Champions of Cheese Awards.
Last year Westgold unsalted butter won gold and the title of champion butter.
"We know that great butter starts with high quality cream from our shareholders, along with the care and commitment of our skilled butter makers.
"Reaching sales of one million blocks in New Zealand is a real testament to the efforts everyone is putting in to making a product and brand that we can be proud of," Ms Sullivan said.
Westgold butter had been sold around the world for more than 12 years before it was launched domestically, following a complete redevelopment for New Zealanders.
— Janna Sherman, Hokitika Guardian