Born in Dublin, Fallon played both hurling and Gaelic football with his local club, St Vincents.
Earlier that year, he was a substitute on the Dublin team that beat Kilkenny in the Walsh Cup final at Parnell Park by 2–11 to 2–10.
While Fallon was not to win any more silverware with the Dubs thereafter, he made a name for himself at inter-county level as an impressive centre-back, receiving many individual accolades.
He was named at centre-back on the 2006 and 2007 Dublin Blue Stars teams and won a Vodafone GAA All Stars of the Month award in March 2007, having led Dublin at centre-back to victories over Galway and Limerick in the League, thus securing their Division 1 status for the following year.
[3] Fallon missed Dublin's championship campaign in 2009 after he sustained a broken metatarsal against Kilkenny in the National Hurling League.
[12] In 2007, Fallon won his first Dublin Senior Football Championship title with Vincents as an unused sub when they beat St Brigids by 0–12 to 1–7.
They then went on to win a Leinster Senior Club Football Championship in December of that year, beating Tyrrellspass of Westmeath by 2–8 to 0–7, although Fallon did not take part in this game either.