Mary Lou McDonald has been confirmed as the only candidate nominated to replace Gerry Adams as Sinn Féin president.
Mr Adams has led the party since 1983. He announced his intention to stand down in November 2017.
Sinn Féin's ard comhairle (high council) met in Belfast on Saturday to formally ratify the nominee.
Ms McDonald said that no-one would fill the shoes of Gerry Adams, "but the news is that I brought my own".
A special party conference to elect the new leader will be held on 10 February.
It means the party is set to be led by a woman for the first time in its modern history.
The last female president was Margaret Buckley, who led the party between 1937 and 1950, however, Sinn Féin has suffered a number of splits since Ms Buckley's time as leader.
Ms McDonald said she "did not for a moment underestimate the scale of this undertaking on a personal and political level".
"I grew up watching Gerry Adams on the telly, l would certainly never have guessed that come February 10 2018, that I would be the boss of him," she said.
"The truth is no-one will ever fill Gerry Adams' shoes, but the news is that I brought my own.
"I will fill my shoes, I will walk in my shoes and we together over the coming years will walk a journey that is full of opportunities, full of challenges but I believe which marks a defining epoch, a defining chapter in our achievement of a united Ireland and the ending of partition."
Mary Lou McDonald had in the past said she would like to see a contest for the Sinn Féin leadership, however she didn't get her wish.
She takes over from Gerry Adams at an interesting time in Irish politics; with an expected abortion referendum, on-going Brexit negotiations, possible general and presidential elections in the Republic- never mind the negotiations in Northern Ireland to restore devolution.
Ms McDonald is expected to spend most of her time south of the border but as the leader of an all-island party she will also have to keep a close eye on developments in the other jurisdiction.
As she has no paramilitary background the party will be hoping that she may help garner Sinn Féin support in more middle class areas and amongst women.
But the Barry McElduff affair shows the legacy of the Troubles at the moment is never very far away for Sinn Féin - probably no matter who is leader.
Ms McDonald said she believed Irish unity was the best solution "for all of our people including our unionist brothers and sisters".
Mr Adams said his decision to step down as leader was "part of Sinn Féin's 10-year plan for the regeneration and renewal of the party".
He also told the meeting of his concerns that politics in Northern Ireland was "very polarised at this time and that the atmosphere is very toxic".
"It is my view that this is not good for anyone except a small minority of bigots," he said.
Nominations for the presidency closed on Friday at 17:00 GMT, and Ms McDonald was the sole candidate.
Ms McDonald, 48, an English literature graduate from Trinity College Dublin, has been a TD (MP) for Dublin Central since 2011.
Before getting elected to the Dáil (parliament) she was an MEP representing the Dublin constituency - becoming Sinn Féin's first MEP in the Republic of Ireland in 2004.
Her personal story is very different from other leading Sinn Féin politicians.
She comes from a middle-class background and was brought up in Rathgar, which is viewed as one of Dublin's most desirable suburbs.