*Club domestic league appearances and goals, correct as of 13:07, 14 September 2023 (UTC) ‡ National team caps and goals, correct as of 22:33, 14 October 2023 (UTC)
Heffernan was born in Cork.[2] His father Rob and mother Marian are both Olympians, in race walking and 400m relay respectively.[3]
Club career
Heffernan began his career with Ringmahon Rangers, signing for Cork City in 2019.[4] He made his senior debut for Cork City in the 2021 season.[3] In March 2021 he trained with Italian clubs Juventus, AC Milan, Roma and Atalanta,[5][6] and turned professional with Cork in June 2021.[4]
He moved on loan to AC Milan in January 2022.[3][7][8][9][10][11] He made his debut for Milan's under-18 team a few days later.[12] In May 2022 he made his debut for the under-19 team.[13]
His transfer to Milan was made permanent in June 2022.[14][15] He joined English club Newcastle United in August 2023.[16]
International career
Heffernan has played for the Republic of Ireland at youth level.[3][17]