Cox first appeared on the inter-county scene with Kerry during unsuccessful spells with the minor and under-21 teams.[5][6] He later spent several season with the junior team and won All-Ireland JFC medals in 2012, 2015 and 2017.[7][8][9] Cox was drafted onto the Kerry senior football team in 2013 and made a number of National League appearances. His decision to spend the summer in the United States during the team's All-Ireland SFC-winning season in 2014 hastened the end of his inter-county career with Kerry.[10]
Cox transferred to the Éire Óg club in County Roscommon in 2019, a move which made him eligible for the county team.[11] He was part of the Roscommon team that won the Conancht SFC title in 2019.[12]