He began his journalistic career working for the
Evening Press. He presents
Behind Closed Doors on
RTÉ One which details released State Documents. and election and referendum programmes on RTÉ. He was appointed to present the current affairs programme,
Prime Time, in September 2013. He has also written the book
A Makeshift Majority: The first inter-party government, 1948-51, On 31 August 2020, McCullagh began presenting the
Six One News alongside
Caitríona Perry. In September 2022, McCullagh was named as one of four presenters to host
Monday Night Live, a new eight-part current affairs panel series on
RTÉ One, beginning on 3 October. In August 2025, McCullagh was named as the successor to
Claire Byrne as the presenter for
Today With... on
RTÉ Radio 1, and began in November. He signed off from the
Six One News on 31 October. In September 2025, he hosted a series on
Éamon de Valera.
Bibliography • • ==Personal life==