Editing Scarlets (section)

===Celtic League / Pro12 / Pro14 / United Rugby Championship===
{| class="wikitable" style="text-align:center"
|-
! Season !! Position/Round !! Played !! Won !! Drawn !! Lost !! Bonus !! Points
|-
| [[2003–04 Celtic League|2003–04]]
| 1st || 22 || 16 || 1 || 5 || 10 || 76
|-
| [[2004–05 Celtic League|2004–05]]
| 5th || 20 || 9 || 0 || 11 || 10 || 46
|-
| [[2005–06 Celtic League|2005–06]]
| 6th || 22 || 10 || 1 || 9 || 7 || 57{{efn-la|11 teams were involved in this season, so one team did not play each week and were awarded four points instead. Therefore, each team finished the season with eight more points than the table would seem to warrant.}}
|-
| [[2006–07 Celtic League|2006–07]]
| 4th || 20 || 12 || 0|| 8 || 9 || 57
|-
| [[2007–08 Celtic League|2007–08]]
| 6th || 18 || 7 || 0 || 11 || 10 || 39
|-
| [[2008–09 Celtic League|2008–09]]
| 5th || 18 || 9 || 0 || 9 || 4 || 40
|-
| [[2009–10 Celtic League|2009–10]]
| 9th || 18 || 5 || 0 || 13 || 9 || 29
|-
| [[2010–11 Celtic League|2010–11]]
| 5th || 22 || 12 || 1 || 9 || 12 || 62
|-
| [[2011–12 Pro12|2011–12]]
| 5th || 22 || 12 || 2 || 8 || 10 || 62
|-
|rowspan="2"| [[2012–13 Pro12|2012–13]]
| 4th || 22 || 15 || 0 || 7 || 6 || 66
|-
| Semi-final ||colspan="7"| Lost 28–17 v [[Ulster Rugby|Ulster]]
|-
| [[2013–14 Pro12|2013–14]]
| 6th || 22 || 11 || 1 || 10 || 9 || 55
|-
| [[2014–15 Pro12|2014–15]]
| 6th || 22 || 11 || 3 || 8 || 7 || 57
|-
| [[2015–16 Pro12|2015–16]]
| 5th || 22 || 14 || 0 || 8 || 7 || 63
|-
|rowspan="3"| [[2016–17 Pro12|2016–17]]
| 3rd || 22 || 17 || 0 || 5 || 9 || 77
|-
| Semi-final ||colspan="7"| Won 27–15 v [[Leinster Rugby|Leinster]]
|-
| Final ||colspan="7"| Won 46–22 v [[Munster Rugby|Munster]]
|-
|rowspan="4"| [[2017–18 Pro14|2017–18]]
| 2nd, Conference B || 21 || 14 || 1 || 6 || 12 || 70
|-
| Quarter-final ||colspan="7"| Won 46–8 v [[Cheetahs (rugby union)|Cheetahs]]
|-
| Semi-final ||colspan="7"| Won 28–13 v [[Glasgow Warriors]]
|-
| Final ||colspan="7"| Lost 40–32 v [[Leinster Rugby|Leinster]]
|-
|rowspan="2"| [[2018–19 Pro14|2018–19]]
| 4th, Conference B || 21 || 10 || 0 || 11 || 12 || 52
|-
| 7th, Champions Cup Play-off ||colspan="7"| Lost 21–10 v [[Ospreys (rugby union)|Ospreys]]
|-
| [[2019–20 Pro14|2019–20]]
| 3rd, Conference B || 15{{efn-la|Only 15 rounds were played during the [[2019–20 Pro14|2019–20]] season due to the [[COVID-19 pandemic in Europe]].<ref name="behind closed doors">{{cite news |url=https://www.bbc.co.uk/sport/rugby-union/53493901 |title=Pro14 restart: 2019-20 season resumes with derby weekends |website=BBC Sport |date=22 July 2020 |access-date=13 August 2020}}</ref>}} || 10 || 0|| 5 || 7 || 47
|-
| [[2020–21 Pro14|2020–21]]
| 3rd, Conference B || 16{{efn-la|Only 16 rounds were played during the [[2020–21 Pro14|2020–21]] season due to the [[COVID-19 pandemic in Europe]], with the remaining matches replaced by the [[Pro14 Rainbow Cup]] competition.<ref>{{Cite web|title=Guinness PRO14 to Conclude in March Ahead of Rainbow Cup with South Africa's Super Teams|url=https://www.pro14.rugby/latest/pro14/guinness-pro14-to-conclude-in-march-ahead-of-rainbow-cup-with-south-africa-super-teams|access-date=24 December 2020|website=pro14.rugby}}</ref>}} || 8 || 0|| 8 || 7 || 39
|-
| [[2021–22 United Rugby Championship|2021–22]]
| 10th || 18 || 8 || 0 || 10 || 13 || 45
|-
| [[2022–23 United Rugby Championship|2022–23]]
| 14th || 18 || 6 || 1 || 11 || 8 || 34
|-
| [[2023–24 United Rugby Championship|2023–24]]
| 13th || 18 || 5 || 0 || 13 || 7 || 27
|}