"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.