Demolition of old buildings on the site began a few days ago.
The company identified the Porowini Ave site as ideal for a Mitre 10 Mega when the Whangarei District Council decided to extend the road.
The extension, completed last July, changed Porowini Ave from a dead-end to an arterial route linking Tarewa Rd and Okara Drive, exiting near the new stadium and the proposed second harbour crossing.
Mitre 10 had planned to complete the project to coincide with the opening of the extension but the project was delayed by land purchase issues.
The company was originally planning to lease the land from the two owners but in the end , purchased it outright.
Mitre 10 New Zealand Ltd occasionally sells land and buildings on a lease-back arrangement to release funds for new stores - the store at the Regent has been a tenant of its building since 2006 - but national property manager Tony Bullock said the company could well retain the Porowini Ave site.
"We haven't decided," he said.
He said the company was currently pricing the cost of different facets of the megastore. Tenders were being called for the main building contract, closing early next month.
Darryl Tilly, a member of the Mitre 10 New Zealand board and owner/operator of the Whangarei Home & Trade store with his wife June, said he was delighted that a Whangarei building firm was submitting a contract and that a number of local trades and suppliers were involved in the process.
"I've pushed strongly for local builders and suppliers to be given the chance to do this," he said.