University of Limerick As a student at the
University of Limerick, Heffernan joined the senior hurling team during his second year. On 27 February 2016, he was selected at right wing-back when UL faced
Mary Immaculate College in the
Fitzgibbon Cup final. Heffernan ended the game on the losing side following a 1-30 to 3-22 defeat. On 24 February 2018, Heffernan played in a second
Fitzgibbon Cup final when UL faced
DCU Dóchas Éireann. He lined out at right wing-back and collected a
winners' medal following a 2-21 to 2-15 victory.
Nenagh Éire Óg Heffernan joined the
Nenagh Éire Óg club at a young age and played in all grades at juvenile and underage levels before eventually joining the club's top adult team. On 13 September 2014, Heffernan lined out at left wing-back when Nenagh Éire Óg drew 1-20 to 2-17 with
Burgess in the
North Tipperary Championship final. He retained his position for the replay two weeks later and claimed a
winners' medal following the 0-14 to 0-08 victory.
Tipperary Minor and under-21 Heffernan first played for
Tipperary when he joined the minor team in advance of the
2011 Munster Championship. He made his first appearance for the team on 27 April 2011 when he came on as a 39th-minute substitute for
Ray Ralph in a 2-16 to 1-13 defeat by
Waterford. On 15 July 2012, Heffernan lined out at left wing-back when Tipperary faced
Clare in the
Munster final. He scored a point from play and ended the game with a
winners' medal after a 1-16 to 1-12 victory. Heffernan again lined out at left wing-back when Tipperary drew 2-13 to 1-16 with
Dublin in the
All-Ireland final. He retained his position for the replay on 30 September 2012 and ended the game with an
All-Ireland medal following the 2-18 to 1-11 victory. Heffernan was once again eligible for the minor grade in
2013. He played his last game in the grade on 26 June 2013 when he lined out at left wing-back in a 1-17 to 0-17 defeat by
Limerick. Heffernan was drafted onto the Tipperary under-21 team before the
2014 Munster Championship. He was an unused substitute on 16 July 2014 when Tipperary suffered a 5-19 to 1-25 extra-time defeat by Clare. On 16 July 2015, Heffernan made his first appearance for the under-21 team when he was selected at centre-back for Tipperary's
Munster semi-final meeting with Limerick. He ended the game on the losing side following a 3-16 to 3-14 defeat. Heffernan was again eligible for the under-21 grade in
2016. He lined out at left wing-back when Tipperary suffered a 2-19 to 0-15 defeat by Waterford in the
Munster final in what was his last game in the grade.
Senior Heffernan was added to the extended training panel of the Tipperary senior team at the start of the 2014 season. On 7 September 2014, he was a member of the extended panel when Tipperary drew 1-28 to 3-22 with
Kilkenny in the
All-Ireland final. Heffernan was again a panel member for the replay on 27 September 2014, however, Tipperary suffered a 2-17 t 2-14 defeat. On 12 July 2015, Heffernan was selected amongst the substitutes when Tipperary qualified to play Waterford in the
Munster final. He remained as an unused substitute but ended the game with a
Munster Championship medal following Tipperary's 0-21 to 0-16 victory. Heffernan made his first appearance for the Tipperary senior team on 6 March 2016 when he lined out at right wing-back in a 1-18 to 1-17 defeat by Waterford in the
National League. He was later prevented from making his
Munster Championship debut after being ruled out of all hurling activity after suffering a series of concussions. On 10 July 2016, Heffernan won a second Munster Championship medal as an unused substitute after Tipperary's 5-19 to 0-13 defeat of Waterford in the
final. He was again named on the bench for the
All-Ireland final against Kilkenny on 4 September 2016. Heffernan remained on the bench but claimed an
All-Ireland medal following the 2-29 to 2-20 victory. On 23 April 2017, Heffernan lined out as a substitute when Tipperary suffered a 3-21 to 0-14 defeat by
Galway in the
National League final. Tipperary qualified for a second successive
National League final on 8 April 2018 with Heffernan lining out at right wing-back. He ended the game on the losing side following a 2-23 to 2-17 defeat by Kilkenny. On 29 June 2019, Heffernan was selected amongst the substitutes when Tipperary qualified to play Limerick in the
Munster final. He was introduced as a substitute for
James Barry but ended the game on the losing side following a 2-26 to 2-14 defeat. On 18 August 2019, Heffernan was selected at left corner-back when Tipperary faced Kilkenny in the
All-Ireland final. He ended the game with a second All-Ireland winners' medal - his first on the field of play - following the 3-25 to 0-20 victory. He ended the season by receiving an All-Star nomination. ==Career statistics==