Club

Heffernan began his playing career with his local club Blackrock and enjoyed some initial success. He won a county junior title in the early 1990s, however, after a brief period in the senior ranks Blackrock returned to junior status once again. A move to Mallow in the early 2000s saw Heffernan join the local club there, where he won a junior league title in 2007.

In 2009 Heffernan transferred back to his home club Blackrock where he joined the team as goalkeeper. It was a successful return as Blackrock secured the county junior title that year. Heffernan's club later represented the county in the provincial series of games and even reached the final. Cork champions Fermoy provided the opposition on that occasion, however, it was Blackrock who secured a narrow 1–12 to 0–14 victory and Heffernan collected a Munster winners' medal.^[2] An All-Ireland final with St. Colmcille's of Tyrone providing the opposition. Blackrock had little difficulty in disposing of the Ulstermen on a score line of 1–18 to 0–9. Heffernan kept a clean sheet again while also collecting an All-Ireland club winners' medal.^[3]

Inter-county

Heffernan first came to prominence on the inter-county scene as a member of the Limerick senior hurling team in the early 1990s. He made his championship debut in 1991, however, he remained a fringe player for his first few seasons on the team.

By 1994 Heffernan was a key member of the full-forward line and played in his first Munster final. Provincial whipping boys Clare were the opponents and a rout took place. A 0–25 to 2–10 score line gave Limerick the win and gave Heffernan his first Munster winners' medal.^[4] Limerick subsequently qualified to meet Offaly in the All-Ireland final. It looked as if Heffernan's side were going to make history and claim the title as Limerick had a five-point lead with as many minutes left. Offaly suddenly sprang to life following a Johnny Dooley goal from a close-in free. Following the puck-out Offaly worked the ball upfield and Pat O'Connor struck for a second goal. The Offaly forwards scored another five unanswered points in the time remaining to secure a 3–16 to 2–13 victory. It was a bitter blow for Limerick who looked as if they had one hand on the Liam MacCarthy Cup.

Limerickregrouped and contested the a second Munster final in succession in 1995. Clare were the opponents once again, however, the roles were reversed on this occasion with victory going to the men from the banner county. Heffernan left the inter-county set up following this defeat. He returned briefly in 2003 at the behest of new manager Pad Joe Whelahan, however, his second coming was short-lived.^[5]

Early experience

After retiring Heffernan pursued a career in coaching, gaining experience in his native Limerick where he became involved with several clubs, including Kilmallock, Murroe-Boher and his native Blackrock. He enjoyed little success with these early endeavours. In 2007 Heffernan took charge of Bride Rovers GAA Club in east Cork and guided the team to the semi-finals of the county senior championship.^[6]

Kerry

In late 2007 Heffernan was appointed manager of the Kerry senior hurling team for a one-year term.^[7] His first season in charge got off to a good start as 'the Kingdom' only lost one game in the group stage of the National Hurling League. This allowed Heffernan's side to advance to the semi-final of the competition, however, Carlow won the game by 1–19 to 3–4.^[8] In the subsequent Christy Ring Cup Kerry topped their group and qualified for a home quarter-final against old rivals Carlow. It was one of the toughest draws and, in spite of home advantage, Kerry were heavily defeated by 2–4 to 1–14.

Heffernan failed to secure silverware but was reappointed as manager for a second season at the end of 2008.^[9] This reappointment was short-lived as Heffernan subsequently stepped down before the start of the season citing personal reasons.^[10]

St. Brendan's Ardfert

In 2010 Heffernan was appointed trainer of the St. Brendan's Ardfert Club in County Kerry. He managed them to the semi-final stage of the County Championship where St. Brendan's were defeated by Ballyduff.

Mallow

In 2010 Heffernan took charge of the Mallow Intermediate Hurling Team. After initial success with a victory over Castlelyons in the Championship, Heffernan's side were defeated in the second round. In the 2011 Heffernan was appointed as the Mallow U21 Hurling Manager.

Limerick

In September 2010 Heffernan was named as a selector along with former teammates Ciarán Carey and T. J. Ryan in Dónal O'Grady's new management team to oversee the Limerick Senior Hurling Team for 2011.

Mullinahone

In 2012 he was appointed manager of Mullinahone Senior Hurling Team.