The company also helped in the investigation, including providing CCTV camera footage.
Police who went to Te Weri's home found a distinctive packet of 20 needles, with one missing.
They were confident the missing needle was the same one found within the food and the incident was all "an honest mistake", Detective Inspector Ross McKay says.
"The woman did the right thing reporting this incident, as did the business. There was no malicious intent here."
Te Weri did not respond to a Chronicle attempt to contact her, and had removed the post from her Facebook page.
McDonald's appreciated how quickly police were able to resolve the matter, Kenny said.