These sports are - rugby sevens, sailing, taekwondo and weightlifting.
Their participation is setting a pathway for the Games to become continental.
It will be the first time the two countries have taken part in the Games since the event started in 1963.
The Pacific Games Council (PGC) approved a proposal to allow Australia and New Zealand to take part following an agreement between the Oceania National Olympic Committee and the Pacific Games Council.
Oceania is the only region without a Continental Games and athletes from the region had to go to other competitions and regions to try to qualify for the Olympics.
The four sports Australia and New Zealand will be allowed to compete in initially were chosen because it is believed that the other Pacific countries could compete against them.