Muiris was Senior Director of Marketing with Bord Bia, the Irish Food Board between 1995 and 2007. He also worked for 12 years with the Irish Export Board where he was Manager for East Asian markets and Director of the Italian market, based in Milan for 5 years. He has carried out export trade development assignments on behalf of the EU in Moldova and Kosovo.

Muiris lectures on marketing and distribution channels as part of the Executive Management and M.B.A Programme at the Michael Smurfit Graduate Business School, University College Dublin.