An election to the 57th Parliament of the United Kingdom for the constituency area of Islwyn, held as part of the general election on 8 June 2017.
Labour hold by Chris Evans with a majority of 11,412 - 31.6% - on a turnout of 64.2%.
Candidates
| Name | Party | Vote | Vote share | Vote change |
| EVANS, Chris | Lab / Co-op | 21,238 | 58.8% | 9.9% |
| THOMAS, Dan | Con | 9,826 | 27.2% | 12.1% |
| JONES, Darren | PC | 2,739 | 7.6% | -3.1% |
| SMYTH, Joe | UKIP | 1,605 | 4.4% | -15.1% |
| KIDNER, Matthew | LD | 685 | 1.9% | -0.8% |
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 56,256, having a valid vote count of 36,093 and an invalid vote count of 78.
Result declared at 01:54 on 9 June 2017.