The wide one-way corridor leading to the Southern and Northwestern Motorways was initially closed to traffic between Wellesley and Cook Sts.
All lanes have since reopened but motorists are being warned to expect delays as traffic returns to normal.
The Serious Crash Unit was investigating the accident. Officers were seen photographing and marking the crash scene.
Matt Young told the Herald there was a loud sound as the pedestrian was struck.
"I heard a very large bang."
He said people rushed to the pedestrian's aid but the man appeared to be lifeless.
Young, who was sitting on his central city balcony, called emergency services.
He said the man was about 15m from a controlled crossing.
Auckland Transport said the crash had led to long delays in the area and motorists should consider a different route.
