Access to turn on to Tennyson St will be available (as signed) but may be delayed at times, the council says.
The offices will not open to the public until Tuesday, the relocation continuing in stages with teams from the three agencies progressively moving in by mid-October.
It's the biggest single move of government services in Napier since the agencies' presence was established in the then-new Vautier and Dalton Houses more than 30 years ago.
Until about five years ago, Dalton House also housed police district headquarters staff, who are now based in the new district headquarters and Hastings police station.
Acting Ministry of Social Development (MSD) regional commissioner Karen Bartlett, who will attend the opening, said about 250 staff will be based in the new building, including the MSD East Coast Regional Office, Napier Service Centre and the Centralised Services Hawke's Bay Unit, along with Oranga Tamariki and Kāinga Ora staff.
The regional office team, led by Bartlett, cover the communities of Gisborne, Wairoa, Napier-Hastings and Central Hawke's Bay.
There will be both public and staff car parking in and around the building, with staff who use government cars having access to a basement carpark.
Local kaumātua will lead the 5.30am blessing and dedication, with staff and managers of the three agencies, iwi and invited community partners and stakeholders in attendance.