Enterprise Ireland is targeting a 50% increase in exports from its client companies to the rest of the Eurozone by 2020, as it tries to persuade firms to diversify away from the UK.
Firms backed by the agency, which helps Irish firms increase global growth, reported record export sales of €21.6bn (£18bn) last year - up 6% on 2015.
But export growth to the UK slowed considerably, due primarily to the Brexit-induced weakening of the pound, with food exports hit in particular.
Julie Sinnamon, Enterprise Ireland chief executive, said that while the UK will remain Enterprise Ireland's key market for the coming years, the agency will work to continue to grow the rest of the world at a faster rate. At the same time, UK growth is forecast to be flat.
"While the UK continues to be our number one market, what these results are really saying is, Brexit has actually impacted already," Ms Sinnamon said.
"We know that over the next two years, as negotiations go on, companies need to start that journey. They need to start increasing their focus on markets outside of the UK."
Taoiseach Enda Kenny said many companies have not yet put in place the required plans to deal with Brexit. "I think it is true to say that many companies have not prepared for the situation that will arise from Brexit, because we don't know the details of what will emerge yet."
But he said businesses cannot wait for the outcome of the talks.