Long's form for Reading in the 2005–06 season earned him four Republic of Ireland U19 caps.
Due to injuries to his Reading teammate Kevin Doyle and Sunderland's Stephen Elliott, he earned his first senior cap for the Republic of Ireland in their 2–1 win away to San Marino on 7 February 2007.

When Long earned his second cap as a substitute against Slovakia on 28 March 2007 he became the first person to play both hurling and international football at Croke Park, having been part of the Tipperary team for the All-Ireland Minor semi-finals in 2003 and 2004.
Long scored his first international goal in a friendly 1–1 draw against Bolivia on 26 May 2007, and followed this with a brace in Ireland's 4–0 win over Denmark on 22 August 2007.
He was nominated as the Football Association of Ireland Young Player of the Year for 2007.

In March 2011, Long was brought on early to replace the injured Kevin Doyle in a UEFA Euro 2012 qualifier against Macedonia in Dublin.
His performance was rewarded with a start in Ireland's next game against Uruguay in which Long scored the first of Ireland's goals with a header in a 2–3 loss.
On 26 May 2012, Long scored when he headed the winner in a 1–0 win over Bosnia and Herzegovina.
He played in UEFA Euro 2012, coming off the bench against Croatia and Italy.

On 29 May 2013, Long scored his ninth goal for Ireland, a header against England at Wembley Stadium, a match which finished 1–1.
He then captained Ireland for the first time on 2 June 2013 against Georgia, a match which Ireland won 4–0.
On 5 March 2014, Long scored his 11th goal for his country in a 2–1 loss to Serbia.

On 29 March 2015, Long came off the bench to score a last-minute equaliser against Poland in 2016 Euro qualifier.
On 8 October 2015, Long again came off the bench to score the winning goal against reigning world champions Germany in another 2016 Euro qualifier in the Aviva Stadium.
Long's form for Reading in the 2005–06 season earned him four Republic of Ireland U19 caps. Due to injuries to his Reading teammate Kevin Doyle and Sunderland's Stephen Elliott, he earned his first senior cap for the Republic of Ireland in their 2–1 win away to San Marino on 7 February 2007.
When Long earned his second cap as a substitute against Slovakia on 28 March 2007 he became the first person to play both hurling and international football at Croke Park, having been part of the Tipperary team for the All-Ireland Minor semi-finals in 2003 and 2004. Long scored his first international goal in a friendly 1–1 draw against Bolivia on 26 May 2007, and followed this with a brace in Ireland's 4–0 win over Denmark on 22 August 2007. He was nominated as the Football Association of Ireland Young Player of the Year for 2007.
In March 2011, Long was brought on early to replace the injured Kevin Doyle in a UEFA Euro 2012 qualifier against Macedonia in Dublin. His performance was rewarded with a start in Ireland's next game against Uruguay in which Long scored the first of Ireland's goals with a header in a 2–3 loss. On 26 May 2012, Long scored when he headed the winner in a 1–0 win over Bosnia and Herzegovina. He played in UEFA Euro 2012, coming off the bench against Croatia and Italy.
On 29 May 2013, Long scored his ninth goal for Ireland, a header against England at Wembley Stadium, a match which finished 1–1. He then captained Ireland for the first time on 2 June 2013 against Georgia, a match which Ireland won 4–0. On 5 March 2014, Long scored his 11th goal for his country in a 2–1 loss to Serbia.
On 29 March 2015, Long came off the bench to score a last-minute equaliser against Poland in 2016 Euro qualifier. On 8 October 2015, Long again came off the bench to score the winning goal against reigning world champions Germany in another 2016 Euro qualifier in the Aviva Stadium.
Shane Long