Accountancy firm EY has revised downwards its economic forecast for both this year and next year on the back of weaker global outlook.
EY's latest Economic Eye report said that growth for 2019 is now projected at 3.7%, down from the rate of 4.1% it had projected in June. This prediction is based on the assumption of an orderly Brexit.
Next year's growth forecast has also been cut to 3% from 3.3% - again based on the UK leaving the EU with a deal.
But EY cautions that economic growth here will fall to just to 1.3% next year if Britain leaves the EU without a deal.
Meanwhile, EY also said that a no-deal Brexit is projected to be sufficient to push Northern Ireland into recession as it predicts that the economy there is expected to contract by 0.6% next year.
It also predicts that a no-deal would cut 60,300 jobs across the island of Ireland by 2022 - 41,500 in the Republic and 18,800 in Northern Ireland.
Professor Neil Gibson, chief economist for EY Ireland, said the external economic climate is as challenging as it has been for a decade, adding that the dual threat of trade wars and Brexit have the potential to derail the country's rapid growth.
The economist said that estimates of a no-deal impact vary considerably, but they all suggest there will be a cost in the form of disruption across the island.
"Regardless of the overall macro impact, the local and firm-specific effects could be devastating for some, with no-deal job losses likely to have a very particular sub-regional pattern," Mr Gibson said.
He said there is no doubt that the resilience and adaptability of businesses will be tested, but added that the "remarkable level of growth and job creation over the last five years is no small feat and places Ireland on a solid footing."