"The 25,000 Big Mac giveaway is proving popular with Kiwis, with over half the burgers redeemed so far," he said.
"But if you fancy a Big Mac for dinner, there's still time and burgers available.
"The McDonald's app has also taken over the number one spot in the App Store."
New Zealand Managing Director Dave Howse said the company wanted the entire country to celebrate the 50th birthday milestone with them.
New Zealand's first McDonald's restaurant opened in Porirua in 1976.
There are now more than 165 McDonald's restaurants across the country, 85 per cent of which are owned and operated by local business men and women.
McDonald's is the primary supporter of Ronald McDonald House Charities New Zealand, who keep families close while their children are in hospital.