She was the only person nominated to succeed Gerry Adams, who has held the position since 1983
Sinn Féin's Mary Lou McDonald is set to succeed Gerry Adams as the party's leader.
The party's deputy leader and Dublin Central TD was announced as president-elect at a Sinn Féin AGM in Belfast this morning, a day after nominations for the leadership closed.
Deputy McDonald's nomination is expected to be ratified at a special Ard Fheis next month.
Gerry Adams has been leader of Sinn Féin since 1983, and announced his intention to stand down last year.
Mary Lou McDonald was originally a member of the Fianna Fáil party before joining Sinn Féin.
After a stint in the European Parliament, she became a TD in February 2011.
Thanking party members today, Deputy McDonald said: "I want to say at the very outset that I don't for a moment underestimate the scale of this undertaking - both on a personal level and indeed on a political level.
"The truth is, and so many of you have said to me quite correctly 'you have very big shoes to fill'. The truth is that no-one will ever fill Gerry Adams' shoes... I won't fill Gerry's shoes - the news is I've brought my own."
She added: "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 and full of challenges - but I believe marks a defining chapter in our achievement of a united Ireland."