Gosper, who won a silver medal for Australia in the 4x400m relay at the Melbourne Olympics in 1956, will be replaced by Robin Mitchell of Fiji.
The 75-year-old was honoured with an Australian Sports medal in 2000 for services to athletics and the Olympic movement.
New Zealand Olympic Committee secretary-general Barry Maister said Gosper's departure would be a huge loss.
"Kevan has a huge involvement in the Pacific . . . he's well known, he's well-respected and has a huge knowledge of the Olympic Games," Maister said.
"So, yes, he's a big loss, but I think after 20 years it is appropriate to move on.
"What is really great is the Oceania convention has got it first Pacific Islander. Robin Mitchell is very highly respected. I think it was pretty clear when he stood there wouldn't be many people standing against him.
"It was a good process and we are very pleased to have Robin heading the Olympic movement in this part of the world," Maisters said.
He described Mitchell as one of "the workers of the organisation".
"Robin has huge personal contacts and understands the organistation . . . and is our highest-flying member in this region."
