Tony Campbell, who is now at the helm of the Thames St business, acknowledged it was a milestone in the Campbell family history.
It was also quite special, and fairly rare, to have had five-generations involved with a business, he said.
The business was started by Robert Campbell and later taken over by Robert's sons, Laurie and Bruce, whose business was known as Campbell Brothers Butchery, before Laurie's son, Roy, took over in 1975.
Roy's son, Tony, started his apprenticeship at the business in 1980, while Tony's eldest son Jason also works at the butchery.
Tony Campbell has seen many changes in the industry, particularly in the last 20-25 years in the way that meat is sold, and also in the different cuts.
In 1980, there were 14 butcher shops in Oamaru - now there were two - and that was a trend throughout New Zealand.
Consumers were now looking for "ready to eat products" that were quick and easy to prepare, moving away from the days of the big Sunday roast, he said.
Campbells Butchery had spread out of Oamaru, supplying supermarkets in the lower South Island, as well as restaurants and cafes, Oamaru, Dunedin and Southland Hospitals, and rest-homes.
It also produced pie meat.
The business has a strong retail outlet in Oamaru, with a regular clientele, and did a lot of private processing, including wild meat for hunters.
Becoming involved with the Oamaru Farmers Market, which began last year, had also been good, Mr Campbell said.
As much as possible, meat was sourced locally, giving the business a point of difference and quality control. The business employs 22 staff which reached a peak of about 30.
Business was going "really well".
However, it was always quieter during the winter months, and so a good time for maintenance, before preparations began for the busy summer period and Christmas hams.
Mr Campbell reckoned he was always destined to be a butcher, recalling helping his parents, Roy and Heather, when he was "a wee boy" when they were packing meat at nights at the butchery, and also helping in his school holidays.
He had no regrets about the career move and the business had "looked after" the Campbell family for 100 years as well as the staff and their families.
He was still happiest in the butchery, rather than the office, he said.
He also enjoyed living in Oamaru, saying it was central as far as distribution for the business was concerned, and also a lovely town in which to bring up a family.
Peter Wallace, who became office manager four years ago, was the first non-Campbell to handle the finances of the business.