An election to the 56th Parliament of the United Kingdom for the constituency area of Llanelli, held as part of the general election on 7 May 2015.
Labour hold by Nia Griffith with a majority of 7,095 - 18.4% - on a turnout of 65.0%.
Candidates
| Name | Party | Vote | Vote share | Vote change |
| GRIFFITH, Nia | Lab | 15,948 | 41.3% | -1.1% |
| WILLIAMS, Vaughan | PC | 8,853 | 23.0% | -7.0% |
| REES, Kenneth | UKIP | 6,269 | 16.3% | 13.5% |
| SAXBY, Selaine | Con | 5,534 | 14.3% | -0.0% |
| PHILLIPS, Cen | LD | 751 | 1.9% | -8.5% |
| SMITH, Guy | Green | 689 | 1.8% | - |
| CAIACH, Siân | PFGG | 407 | 1.1% | - |
| JONES, Scott | TUSC | 123 | 0.3% | - |
Under section 13(b) of the Representation of the People Act 1985, a candidate gaining 5% or less of the vote share will forfeit their deposit.
An electorate of 59,314, having a valid vote count of 38,574 and an invalid vote count of 40.
Result declared at 02:13 on 8 May 2015.