Construction of the two-lane new roadway will include road widening, a shared footpath, new bus stops and shelters and more.
The work was due to be completed by June 2021.
The $8 million upgrade was being jointly funded by Waka Kotahi New Zealand Transport Agency and the council.
Western Bay Mayor Garry Webber said while the project will create some short term traffic disruption and inconvenience, the upgrade was an essential link in Omokoroa's roading network to cater for subdivision development and population growth.
"Ultimately, this project will provide a safer environment and amenity for residents, motorists, cyclists, and pedestrians.," he said.