Plaid Cymru has selected Mabon ap Gwynfor to contest Dwyfor Meirionnydd in the next Welsh Assembly elections, taking place in 2021.
Mr ap Gwynfor is the grandson of Plaid Cymru's first ever MP, Gwynfor Evans.
The Denbighshire County councillor was announced following a hustings event in Pwllheli on Saturday.
The constituency is represented in the Senedd by Lord Dafydd Elis-Thomas, who left the party to become an independent AM in 2016.
Mabon ap Gwynfor said: "I'm grateful to party members for putting their faith in me as their candidate to win back the seat".
He added: "It's an exciting time for Plaid Cymru. We are charting a course that offers the best and brightest future for the people of Wales.
"Now the work must begin to reach out to the people of Dwyfor Meirionnydd and build on Plaid's strong track record of standing up for the constituency, our European values and for Wales."