Tipperary Minor Cahill first became involved in inter-county management as a selector on
Declan Ryan's Tipperary minor hurling management team in 2007. After helping guide the team to the
Munster Championship title after a defeat of
Cork, Tipperary later beat Cork for a second time that season in the subsequent
All-Ireland final. Cahill's second and final season as a selector with the Tipperary minor team ended with defeats by Cork and
Kilkenny. In September 2013, Cahill returned to inter-county management when he was appointed manager of the Tipperary minor team. His first season in charge ended with a 1-23 to 0-12 defeat by
Clare in the Munster Championship. Cahill's second season as manager saw him guide Tipperary to the Munster Championship title after a three-point defeat of
Limerick. On 6 September 2015, Tipperary suffered a 4-13 to 1-16 defeat by
Galway in the All-Ireland final. Cahill remained as manager of the team for a third season in 2016 and guided the team to a second successive Munster Championship title after a 1-24 o 0-10 defeat of Limerick. On 4 September 2016, Cahill's minor team won the All-Ireland title after a 1-21 to 0-17 defeat of Limerick in the final. Cahill's four-year tenure as Tipperary minor hurling manager ended with a three-point defeat by Cork in 2017.
Under-21 and under-20 Cahill was appointed manager of the Tipperary under-21 hurling team in November 2017. After being heavily defeated by
Cork in the
Munster Championship final, Cahill guided Tipperary to an
All-Ireland final appearance against the same opposition on 26 August 2018. An injury-time goal from
Conor Stakelum secured a 3-13 to 1-16 victory. As a result of the under-21 success, Cahill refused to rule himself out of the running for the vacant Tipperary senior hurling manager post stating: "The Tipp senior job never really came into my mind to be honest, but I’m absolutely honoured to be linked to it. We'll see." In spite of this, he remained with the underage set-up, becoming the Tipperary under-20 manager. On 23 July 2019, Cahill guided Tipperary to the inaugural
Munster Championship title following a 3-15 to 2-17 defeat of Cork in the final. Both sides met again in the
All-Ireland final on 24 August 2019, with Tipperary recording a 5-17 to 1-18 victory and a third successive championship defeat of Cork.
Waterford Cahill was ratified as manager of the
Waterford senior hurling team on 30 September 2019. His first major action as manager saw him drop
Noel Connors and
Maurice Shanahan from the panel. This was later followed by the retirement of
Michael "Brick" Walsh. In August 2021, Cahill confirmed that he would be staying on as manager of the Waterford senior team for at least another year, after turning down the opportunity to manage the
Tipperary hurling team. On 2 April 2022,
Waterford won the
2022 National Hurling League after a 4-20 to 1-23 win against
Cork in the final. On 15 July 2022, Cahill stepped down as Waterford manager after three years in charge, after opting against taking a fourth year.
Tipperary ====
2023 Season==== On 18 July 2022, Cahill was named as the new manager of the
Tipperary county hurling team on a three year term, replacing
Colm Bonnar. In 2023 he was assisted by coach Michael Bevans and selectors
Pádraic Maher, Declan Laffan and TJ Ryan. ====
2024 Season==== In the
2024 Munster Senior Hurling Championship, Tipperary lost by eighteen points to
Limerick in round 1 before drawing with
Waterford a week later in
Walsh Park. In round 3 they lost to
Cork by eighteen points on a 4-30 to 1-21 scoreline which eliminated Tipperary from the Munster and All-Ireland Championships. In their final game on 26 May they lost to
Clare by three points. ====
2025 Season==== On 20 July in the
2025 All-Ireland final, Tipperary defeated
Cork by 3-27 to 1-19 and claim a
29th All-Ireland title. ==Personal life==