Mairia Cahill has been elected to the Seanad on the first count.
The Belfast woman comfortably won today's by-election - prompted by the retirement of Labour Party senator Jimmy Harte.
Ms Cahill secured 122 first preference votes and was declared to have won the seat following the first count.
The young mother, who was raped by an alleged senior IRA figure before being subjected to a kangaroo court, will formally be sworn in as a Labour senator next week.
Fianna Fáil candidate Dr Keith Swanick secured 38 votes, while Sinn Fein's Sinead Burke secured 18 votes. Independent candidate Jerry Beades secured 10 votes.
The campaign was hit by controversy after Ms Cahill was forced to explain her connections with a dissident group known as Republican Network for Unity (RNU).
Yesterday, she apologised for joining the group and said it happened at a vulnerable point in her life.