The Member of the Senedd for Ynys Môn, Rhun ap Iorwerth, will stand as an MP for Plaid Cymru on the island in the next general election.
The former BBC Wales journalist has represented the seat in the Senedd since 2013 and will now challenge Conservative MP Virginia Crosbie, in the Ynys Môn constituency.
Plaid has not held the Westminster constituency of Ynys Môn since 2001, when Labour’s Albert Owen won the seat.
Mr Owen stood down at the 2019 general election, when Ms Crosbie won the seat with a majority of 1,968.
Mr ap Iorwerth said: “This evening I was given unanimous backing by Plaid Cymru to be its next candidate as MP for Ynys Môn.
“Representing Ynys Môn in the Senedd is such a huge honour, but as our own Parliament grows in stature, so it’s vital to make sure Ynys Môn and Wales’ voice is heard in the UK Parliament.
“The cruel budget announced last week, trashing the economy and squeezing the poorest whilst cutting taxes for the super-rich makes me even more determined to stand up for our community and to show that Wales deserves better than this.
“I want to represent everyone on Ynys Môn. We can do this together.”
Under the rules which govern the Senedd Mr ap Iorwerth would have to step down if he won the election and became a Westminster MP.