Police were called just before 7pm, after the person jumped from the Waiwhakaiho River bank upstream from Te Rewa Rewa Bridge, although police originally reported they jumped from the birdge.
They did surface once but were then not seen again.
An extensive search was undertaken, but the person was found dead near the river mouth at 9.30pm, police said.
A rāhui has now been placed on the river.
Ngāti Tāwhirikura hāpu has placed a customary prohibtion of water activities from the river mouth to the Telecom waterhole (Rimu Street).
Police said
The rāhui will be lifted next Sunday morning.