"Every single piece of refrigeration and shelving will be ripped out and brand new replacements put in," said Mr Dyson, who bought Westend New World four years ago after previously owning and selling New World Kawerau, and the Katikati Four Square.
Mr Dyson - who started his supermarket career as a 15-year-old trolley boy - said he was financing the $8m refurbishment cost himself, but was convinced it was a good investment.
"We've got a very good market here in Rotorua, and we want to keep [our New World] modern and updated," he said, adding that it had been about 18 years since any major changes had been made to the premises.
Rotorua mayor Steve Chadwick said the supermarket space was becoming more competitive with new entrants in the market.
"It's great that New World is picking up on the new wave of customer food demand," she said.
She added that a decade of population stagnation had turned around in the city last year.
"Obviously that's compelling for their business case and New World's investment reflects the growth that's been happening in Rotorua."
Mr Dyson said the renovations got under way with extensive plumbing changes because the supermarket was converting from 404A gas to more environmentally sound CO2 gas for all its refrigeration.
"The CO2 is a higher pressure gas than 404A and can't go in the same piping, so the whole shop has had to be re-piped and a new pump room installed," he said.
New LED lighting throughout would cost about $100,000, but would be brighter and in the longer term more energy efficient and cheaper to operate, he said.
"It all costs a lot initially, but there are savings, and [the lighting and refrigeration] is more environmentally friendly so there will be cost savings longer term."
The first refurbished section to formally open will be the liquor department this Friday. The carpark - only half of which is currently accessible because of the changes - will reopen with the new covered walkways in four to six weeks, he said.
