The former Ulster Unionist Westminster candidate, Paula Bradshaw, has joined the Alliance Party.
Ms Bradshaw quit the Ulster Unionists recently after missing out on selection for next year's Assembly elections.
On Thursday, she said that she was "very excited about starting this new chapter".
Ms Bradshaw stood under the joint Ulster Conservatives and Unionists' banner at the general election in May.
In the UUP selection procedure in September, she finished behind the health minister Michael McGimpsey, businessman Mark Finlay and Castlereagh councillor Michael Henderson.
At the time, she said she was very disappointed by the decision and was considering her future in politics.
On Thursday, Ms Bradshaw said: "I would like to thank the many people who have offered me so much support over the past month or so.
"They persuaded me that, whatever I did, I must continue in politics, and to try to make politics work for people who currently feel excluded from it.
"When I sought a vehicle to do that, the Alliance Party was the natural place to turn," she said.
Party Leader David Ford said that he was "very pleased to welcome Paula into the Alliance Party".
"It's great that exciting politicians like her realise that Alliance is the only genuine party of a shared future."