An election to the 56th Parliament of the United Kingdom for the constituency area of Arfon, held as part of the general election on 7 May 2015.
Plaid Cymru hold by Hywel Williams with a majority of 3,668 - 13.7% - on a turnout of 66.3%.
Candidates
| Name | Party | Vote | Vote share | Vote change |
| WILLIAMS, Hywel | PC | 11,790 | 43.9% | 8.0% |
| PUGH, Alun | Lab | 8,122 | 30.3% | -0.1% |
| BARRY, Anwen | Con | 3,521 | 13.1% | -3.8% |
| WALL, Simon | UKIP | 2,277 | 8.5% | 5.9% |
| SHULTAN, Mohammed | LD | 718 | 2.7% | -11.4% |
| JONES, Kathrine | SL | 409 | 1.5% | - |
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 40,492, having a valid vote count of 26,837 and an invalid vote count of 95.
Result declared at 02:17 on 8 May 2015.