Shirley Hodges won the Baruc ward seat on Vale of Glamorgan Council with 856 votes – 48 per cent of the vote – almost double that of the Reform Party candidate in second place.
The victory follows the departure of Mark Hooper, who was elected to the Senedd, triggering the by-election.
Cllr Hodges said: “I am delighted that so many people in Baruc ward put their trust in me to represent them.
“As a councillor, I will be focusing my scrutiny on how the Vale of Glamorgan treats Barry in general, with a particular focus on the areas I represent – Barry Island, the Waterfront, Garden Suburb, Knap, Romilly Park and the streets around Harbour Road.
“Barry is a great place, with a proud history, of which I raise awareness every day through the Victorian Barry Experience.
“I won’t be afraid of challenging the Labour Council on their failure to deliver for Barry, and the gap between how the Council see themselves and how real people experience this on the ground.”
She is a long-time Barry Town councillor, since 2004, and editor of the Victorian Barry Experience Facebook page, which has more than 12,500 followers
Cllr Hodges also writes a regular column for Buddy Magazine.
Her predecessor, Mark Hooper, stood down after being elected to the Senedd, in line with new rules that prevent individuals from holding both Senedd and council positions.
Plaid Cymru group leader Cllr Ian Johnson said: “I look forward to working with Shirley Hodges on the Vale Council, where her experience will help us to hold Labour to account in this final year of the current council.”
Conservative and Labour candidates finished third and fourth in the by-election, each securing just over 10 per cent of the vote each.
