Whittaker's last increased the price of its chocolate bars in 2019, also in response to rising production costs.
A spokesperson from Whittaker's said the price increase would come to less than 5 per cent.
"Our costs for ingredients and freight and distribution have continued to rise over the past three years, as well as additional costs for ensuring our ingredients are ethically sourced and working on new more sustainable packaging solutions, and we are now at a point where we are no longer able to absorb them all," the spokesperson said.
"We hope that Whittaker's Chocolate Lovers agree that a small price increase is preferable to any changes to our product size, recipes, product range, use of the finest ingredients, commitment to sustainability, or where we make our chocolate."
The latest price increase comes amid growing concerns about the level of inflation in New Zealand.
Inflation data released in July showed the Consumer Price Index was up 3.3 per cent year-on-year.
This was the biggest increase in nearly 10 years and was driven by higher prices for new housing and petrol, StatsNZ said.
Despite the price increase, many consumers responded to the post saying that they understood the need to increase prices.
One fan of the business said: "We completely understand that prices have to go up. Thanks for not hiding it in smaller packages or changing recipes. We are grateful for good quality New Zealand made."
Others also said they were happy to pay a little more as long as the recipes stayed the same.
Whittaker's is one of New Zealand's most beloved brands.
The company has come on top of the Reader's Digest Most Trusted Brands survey for ten years in a row.