[citation needed] O'Brien joined the Newport club at a young age and played in all grades at juvenile and underage levels.
On 23 October 2016, O'Brien captained Newport in the Tipperary Intermediate Championship final against Thurles Sarsfields.
O'Brien was switched to left corner-back when Tipperary faced Cork in the Munster final on 8 July 2007.
He won a Munster Championship medal as a non-playing substitute on 28 July 2010 following Tipperary's 1-22 to 0-17 defeat of Cork in the final.
[4] On 1 June 2011, O'Brien made his first appearance for the Tipperary under-21 team when he came on as a substitute for James Barry at centre-back in a 4-12 to 1-16 defeat of Waterford.
[9] O'Brien made his first appearance for the team on 22 July when he came on as a 45th-minute substitute for James Barry in a 0-28 to 3-16 defeat of Clare in the All-Ireland quarter-final.