A member of the Na Fianna club in Glasnevin, Horan was the first Dublin-born GAA president since 1924 when Daniel McCarthy finished his three-year term.

A significant development in his tenure occurred at a GAA Special Congress held at Páirc Uí Chaoimh in Cork on 20 October 2019, where delegates voted in favour of the introduction of a second tier Gaelic Football Championship.

[9] Other notable firsts included an address at an ecumenical service celebrating Gaelic games in St Patrick's Cathedral in Dublin on 26 May 2019.

[14] On 21 November 2020 Horan led the GAA in their centenary commemoration of the Bloody Sunday attack on Croke Park by Crown Forces which resulted in the deaths of 14 innocent people.

President of Ireland Michael D Higgins, Taoiseach Micheal Martin and GAA Director General Tom Ryan also laid wreaths in an empty Croke Park due to COVID-19 restrictions.