An election to the 57th Parliament of the United Kingdom for the constituency area of Arfon, held as part of the general election on 8 June 2017.
Plaid Cymru hold by Hywel Williams with a majority of 92 - 0.3% - on a turnout of 68.2%.
Candidates
| Name | Party | Vote | Vote share | Vote change |
| WILLIAMS, Hywel | PC | 11,519 | 40.8% | -3.1% |
| GRIFFITHS CLARKE, Mary | Lab | 11,427 | 40.5% | 10.2% |
| PARRY, Phillippa | Con | 4,614 | 16.4% | 3.2% |
| DAVIES, Calum | LD | 648 | 2.3% | -0.4% |
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 41,367, having a valid vote count of 28,208 and an invalid vote count of 67.
Result declared at 01:59 on 9 June 2017.