Almost $20 million is being invested in the expansion of Sugarloaf Wharf in the latest round of Provincial Growth Funding.
It is expected to increase mussel farming capacity by almost 20,000 tonnes.
In a statement, Deputy Prime Minister Winston Peters said the aquaculture sector in Thames-Coromandel contributed $70m to the district's GDP and was responsible for 350 jobs.
"But the sector has long been significantly constrained by a lack of capacity at Sugarloaf Wharf, which handles 90 percent of the North Island's mussel production," he said.
The funding will build an extended, raised wharf platform to account for rising sea levels, with four new berths to allow increased commercial activity and a separate facility for launching recreational boats.
Peters said the new wharf, Te Ariki Tahi Sugarloaf, would accommodate up to 42,000 tonnes of mussels a year, to meet increased demand from recently granted consents.
"Providing a dedicated recreational boating facility will also bring more visitors to the region and grow exciting new opportunities such as charter fishing, which has long been popular in the Gulf," he said.