Only a handful of stores that didn't have space for pie ovens would not sell Georgie Pie products, the company said.
McDonald's managing director Patrick Wilson said the company had been consulting with customers on Facebook regarding the development of additional Georgie Pie products and two more flavours - which he declined to give further details on - would be added by early next year.
"When we launched the pilot [trial] there was a lot of interest from the public and that's just continued over these past months and it's definitely exceeded our sales expectations," Wilson said. "[Sales are] somewhere in the region of 50 per cent over what we expected."
He declined to provide any numbers on Georgie Pie sales, saying that information was commercially sensitive.
Wilson said opening standalone Georgie Pie stores would not be commercially viable.
"I think the consumers have told us that the way we've positioned Georgie Pie in our restaurants works," he said.
Wilson said the introduction of the pie brand had resulted in only minimal "cannibalisation" of McDonald's other products, such as burgers.
"It seems to have brought back [into McDonald's] lots of lapsed customers."
Cannibalisation occurs when a retailer introduces a new product, or store, that takes away sales of the company's existing products.
McDonald's said that from October 21, eight stores in Gisborne, Wellington, Hawkes Bay and the Bay of Plenty would be used as "seeding restaurants" to train regional staff and test distribution of the product.
The company will then begin distributing the pie ovens, manufactured by Christchurch firm Moffat, to the remaining restaurants as the equipment becomes available.
McDonald's acquired Georgie Pie from supermarket operator Progressive Enterprises in 1996, largely to get hold of its real estate.
The last of the pie chain's outlets closed in the late 1990s, but McDonald's still holds the trademark and intellectual property rights to the brand.