Leanne Wood was unveiled as the new leader of Plaid Cymru at a special event in Cardiff on Thursday.
The former Morning Star columnist takes over from Ieuan Wyn Jones, who is standing down after over a decade in charge of the party.
The race had been contested by three candidates Dafydd Elis-Thomas, Elin Jones and Ms Wood.
Following the elimination of Lord Elis-Thomas in the first round of voting, the contest became all-woman affair, with the peer's second and third preference votes being split between the two remaining candidates.
Ms Woods eventually triumphed after polling 3,326 compared to Elin Jones's 2,494.
Speaking after her election Plaid's new leader said: "I may not be the leader of the official opposition, but I intend to lead the official proposition.
"The proposition that another Wales is possible.
"So here's my message today to the people of Wales - we are your party.
"The People's Party, of Wales, for Wales.
"Together we'll build a new Wales that will be fair, a new Wales that will flourish and a new Wales that will be free."