An election to the 58th Parliament of the United Kingdom for the constituency area of Ynys Môn, held as part of the general election on 12 December 2019.
Conservative gain from Labour by Virginia Crosbie with a majority of 1,968 - 5.4% - on a turnout of 70.4%.
Candidates
| Name | Party | Vote | Vote share | Vote change |
| CROSBIE, Virginia | Con | 12,959 | 35.5% | 7.7% |
| ROBERTS, Mary | Lab | 10,991 | 30.1% | -11.8% |
| AP DAFYDD, Aled | PC | 10,418 | 28.5% | 1.1% |
| JENNER, Helen | BRX | 2,184 | 6.0% | - |
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 51,925, having a valid vote count of 36,552 and an invalid vote count of 121.
Result declared at 02:45 on 13 December 2019.