Dale Farm head David Dobbin was speaking as the processing firm unveiled a new £2.5m cheese packing line at its County Tyrone plant.
It ends a £7m investment at Cookstown that created 60 jobs.
He said the industry wanted a free-trade deal giving access to EU markets.
Mr Dobbin added that a couple of future investment projects would depend on the outcome of trade negotiations with the EU.
But he said the bulk of them would go ahead regardless.
As much as £70m worth of sales is being generated by the Cookstown plant.
Much of the cheese is destined for customers in Britain, with the rest serving markets in Europe, the West Indies and the United States.
Mr Dobbin said the company was "well-hedged" in relation to future trade arrangements.
He said any tariffs would make imports more expensive, allowing UK companies to sell more produce to the domestic market.
If a free-trade deal was concluded with the EU, Dale Farm could continue to grow its European business, he added.
Economy Minister Simon Hamilton attended the launch of the facility that received more than £500,000 pounds of public money.
He said he was keen to work with companies to help them overcome the challenges and seize opportunities the UK's withdrawal from the EU would present.
Mr Hamilton added that agri-food is a key element of the Northern Ireland economy and one that had "defied the odds" during the downturn.
Earlier this month, the first and deputy first ministers wrote to the prime minister calling for an open trading arrangement with the EU and highlighting the importance of agri-food to the wider Northern Ireland economy.
Twenty million pounds of investment in one of Northern Ireland's biggest agri-food companies is set to go ahead regardless of the outcome of negotiations over Brexit.