Former Labour senator Mairia Cahill to become councillor for SDLP
Mairia Cahill will remain a member of the Labour party in the Republic, while serving as a councillor for sister party the SDLP.
Ms Cahill will be co-opted on to Lisburn and Castlereagh Council.
She said she intends to represent everyone "from all traditions and none, to the best of my ability".
The west Belfast woman was plunged into the spotlight in 2010 after she waived her right to anonymity to speak out in a newspaper interview, making allegations she had been raped by a suspected IRA member when she was a teenager in 1997.
She further claimed that the IRA conducted its own inquiry into her account, subjecting her to interrogation and forcing her to confront her alleged attacker.
The man she accused of rape was later acquitted of criminal charges in court after Ms Cahill withdrew her evidence. Charges were dropped against those allegedly involved in the IRA's internal inquiry.
Ms Cahill, who comes from a strongly republican family in west Belfast, said after speaking out she was subjected to "relentless abuse" by republican trolls on social media.
However, Ms Cahill said she would not be intimidated into silence by those trolls.
"If I lived my life being dictated to by trolls, I'd never get anything done," she said.
"They haven't gone away, but I will be concentrating on constituency issues and I hope that those people would do something productive for society also."
In 2015, Ms Cahill joined the Labour party and was elected to the Seanad.
She told Press Association that she is very happy to take on her latest challenge as a councillor.
"I will continue to develop real and meaningful engagement with the Unionist community and I look forward to getting stuck into local issues in the Lisburn council area."
Ms Cahill will replace former SDLP councillor Christine Robb who recently resigned from representing the Killultagh district electoral area for personal reasons.
Mr Eastwood said he is confident that Ms Cahill will be an asset to the party.
"Mairia Cahill has an extremely strong record of speaking out against injustice, maltreatment and inequality; we are confident that her attributes are best placed to compliment the values and vision of the SDLP, and we are delighted she has decided to make the SDLP her political home," he said.
"Politics is too often sadly missing brave voices to call out right from wrong.
"The SDLP has always taken uncomfortable steps to deliver a fair and just society, and I am confident Mairia will play a prolific part in continuing to practice the politics others merely preach, by speaking truth to power."
Read more here: Cahill abused online on a 'demonic basis', says Labour leader