The country's biggest export terminal, based in the northern city of Tauranga, said net profit for the six months ending December 31 was US$28.7 million, up 22 percent from the same period a year earlier.
It said trade volumes across the port over the six-month period increased 9.6 percent while container numbers increased 17 percent from the same period last year.
Port of Tauranga chief executive Mark Cairns said the company expects fiscal-year, after-tax earnings to be around $57 million.
The company expects to benefit from six new shipping services, a higher number of cruise-ship visits and the relocation of dairy giant Fonterra Co-Operative Group's upper North Island export business to Tauranga from the end of January.