| Semi-final | style="text-align:center" colspan=2| No competition |- | 2003–04 | Celtic League | 7th | 51 | style="text-align:center" | N/A | Heineken Cup | Semi-final | Celtic Cup | Quarter-final |- | 2004–05 | style="background: silver"|Celtic League | style="background: silver"|2nd | style="background: silver"|69 | style="text-align:center"| N/A | Heineken Cup | Quarter-final | style="background: gold"|Celtic Cup | style="background: gold"|Champions |- | 2005–06 | Celtic League | 3rd | 66 | style="text-align:center"|N/A | style="background: gold"|Heineken Cup | style="background: gold"|Champions | style="text-align:center" colspan=2| No competition |- | 2006–07 | Magners League | 6th | 54 | style="text-align:center"| N/A | Heineken Cup | Quarter-final | style="text-align:center" colspan=2|No competition |- | 2007–08 | Magners League | 3rd | 48 | style="text-align:center"|N/A | style="background: gold"|Heineken Cup | style="background: gold"|Champions | style="text-align:center" colspan=2|No competition |- | 2008–09 | style="background: gold"|Magners League | style="background: gold"|1st | style="background: gold"|63 | style="text-align:center" |N/A | Heineken Cup | Semi-final | style="text-align:center" colspan=2|No competition |- | 2009–10 | Magners League | 4th | 45 | Semi-final | Heineken Cup | Semi-final | style="background: silver"|British and Irish Cup | style="background: silver"|Runner-up |- | 2010–11 | style="background: gold"|Magners League | style="background: gold"|1st | style="background: gold"|83 | style="background: gold"|Champions | Challenge Cup* | Semi-final | British and Irish Cup | 3rd in pool |- | 2011–12 | RaboDirect PRO12 | 3rd | 67 | Semi-final | Heineken Cup | Quarter-final | style="background: gold"|British and Irish Cup | style="background: gold"|Champions |- | 2012–13 | RaboDirect PRO12| 6th | 54 | Did not qualify | Heineken Cup | Semi-final | British and Irish Cup | Semi-final |- | 2013–14 | RaboDirect PRO12 | 3rd | 74 | Semi-final | Heineken Cup | Semi-final | British and Irish Cup | Quarter-final |- | 2014–15 | style="background: silver"|Guinness PRO12 | style="background: silver"|2nd | style="background: silver"|75 | style="background: silver"|Runner-up | Champions Cup | 3rd in pool | British and Irish Cup | Quarter-final |- | 2015–16 | Guinness PRO12 | 6th | 63 | Did not qualify | Champions Cup | 3rd in pool | British and Irish Cup | 3rd in pool |- | 2016–17 | style="background: silver"|Guinness PRO12 | style="background: silver"|1st | style="background: silver"|86 | style="background: silver"|Runner-up | Champions Cup | Semi-final | style="background: gold"|British and Irish Cup| style="background: gold"|Champions|- | 2017–18 | Guinness PRO14 | 2nd (A) | 69 | Semi-final | Champions Cup | Semi-final | British and Irish Cup | Quarter-final |- | 2018–19