An election to the 57th Parliament of the United Kingdom for the constituency area of Llanelli, held as part of the general election on 8 June 2017.
Labour hold by Nia Griffith with a majority of 12,024 - 29.8% - on a turnout of 67.9%.
Candidates
| Name | Party | Vote | Vote share | Vote change |
| GRIFFITH, Nia | Lab | 21,568 | 53.5% | 12.1% |
| DAVIES, Stephen | Con | 9,544 | 23.7% | 9.3% |
| ARTHUR, Mari | PC | 7,351 | 18.2% | -4.7% |
| REES, Ken | UKIP | 1,331 | 3.3% | -13.0% |
| DANIELS, Rory | LD | 548 | 1.4% | -0.6% |
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 59,434, having a valid vote count of 40,342 and an invalid vote count of 56.
Result declared at 01:09 on 9 June 2017.