Bonnar played for club sides Cashel King Cormacs and Dunhill and was a member of the Tipperary senior hurling team for 13 seasons, during which time he usually lined out at midfield.
At the inter-county level, Bonnar was part of the successful Tipperary minor team that won the All-Ireland Championship in 1982.
From his debut, Bonnar was ever-present as a midfielder and made numerous National League and Championship appearances in a career that ended with his last game in 1998.
At inter-provincial level, Bonnar was selected to play in five championship campaigns with Munster and won Railway Cup medals in 1995, 1996, and 1997.
After an unsuccessful tenure as a selector with the Tipperary senior team, he later guided the Waterford Institute of Technology to four Fitzgibbon Cup titles in six years.
The eighth of thirteen children born to a couple who had strong links to County Donegal, he was educated at the local national school and later attended Cashel CBS.
[1] Bonnar joined the Cashel King Cormacs club at a young age and played in all grades at juvenile and underage levels.
On 28 September 1980, he won a Tipperary Minor Championship medal after lining out at midfield in a 2-11 to 0-07 defeat of Thurles Sarsfields in the final.
He won a third West Tipperary Senior Championship medal on 22 September after Cashel retained the title with a 0-12 to 0-08 defeat of Cappawhite in the final.
On 10 November, Bonnar captained the team from midfield when they faced Holycross-Ballycahill in the Tipperary Senior Championship final.
On 29 July 1993, Bonnar was at midfield when Cashel King Cormacs faced Kickhams in the West Tipperary Senior Championship final.
A subsequent defeat of Antrim allowed Tipp to advance to the All-Ireland final where Galway provided the opposition.
Noel Lane scored the crucial goal for Galway while Nicky English sent a late penalty over the bar for a point.
For the third time in as many years, Tipp faced Galway in the All-Ireland series, however, on this occasion the men from the West were without their star player Tony Keady.
Antrim's relative inexperience robbed the final of any real element of contest and Tipp romped home to a 4–24 to 3–9 win.
[9] Tipp returned in 1991 and defeated Cork in a thrilling Munster final replay giving Bonnar his fourth provincial medal.
Clare was well on top for much of the game, however, Liam Cahill and Eugene O'Neill scored twice for Tipp in the last ten minutes.
[12] On 13 September 1999, Bonnar joined the Waterford senior hurling team's five-man selection committee under Gerald McCarthy.
[13] His first season as a selector and assistant coach saw Waterford finish in second place in Division 1B after the group stage of the National League.
His side failed to make it to the knock-out stage after losing three games and finishing in fifth position in the group table.
Waterford had a mid-table finish in Division 1A of the 2002 National League and failed to make the knock-out stages for the second year in succession.
"[16] Bonnar's fourth and final season with Waterford saw the team fail to make the knock-out stage of the National League for the third year in succession.
Bonnar was confirmed as manager of the Wexford senior hurling team, in succession to John Meyler, on 11 November 2008.
[18] His team was knocked out of the 2009 Leinster Championship at the semi-final stage by Dublin, and lost to Limerick in the qualifiers, leaving them in a situation where they had to play a relegation play-off against Antrim.
Bonnar was unhappy about the possibility that his team could potentially play in Christy Ring Cup rather than the All Ireland Series in 2010.
[19] He and the managers of the other teams involved in the play-offs appealed to the GAA's Disputes Resolution Authority,[20] who took the decision to postpone the relegation final until a future date.
For the fourth time in as many months, Antrim provided the opposition, however, Bonnar's side claimed the title with a 5-23 to 4-15 victory.
[31] Bonnar's side failed to secure a win in Division 1B, however, Carlow managed draws with Galway and Laois.
[34] Carlow lost all four games in the 2019 Leinster Senior Hurling Championship and was relegated to the 2020 Joe McDonagh Cup.
[38][39] On 8 January 2022, in his first game in charge, Tipperary lost to Kerry by 0-14 to 0-17 in Tralee in the quarter-final of the 2022 Munster Senior Cup.