Gerry Adams says the appointment represents the handover of a primary leadership position within the party to a new generation
Michelle O’Neill has been named as the new leader of Sinn Féin in Northern Ireland.
Ms O'Neill, who replaces Martin McGuinness as party leader there, had been serving in Stormont as health minister.
Mr McGuinness resigned from politics last week for health reasons.
The party's president, Gerry Adams said Ms O'Neill's appointment represents "a hugely significant day" for the Sinn Féin movement.
"This is the handover of a primary leadership position from my generation, from Martin's generation, to another generation," he said.
Ms O'Neill was first elected as an assembly member in March 2007.
She has campaigned on issues of equality, autism, disability, mental health and the rights of rural dwellers.
She served in local government as a member of Dungannon and South Tyrone Borough Council from 2005 until 2010 - becoming the first woman to hold the position of mayor of the Dungannon council area.
Following the 2011 assembly election, Ms O'Neill was appointed as Minister for Agriculture and Rural Development.
She was also the first executive minister to decentralise an entire government department - with the relocation of the DARD headquarters to Ballykelly in Derry, Forest Service to Fermanagh, Fisheries to south down and Rivers Agency Headquarters to Cookstown.
In May 2016, she was re-elected as an assembly member for Mid-Ulster and reappointed as minister for health.
She has been active in republican politics since her youth and has held various senior positions within the Sinn Féin party.
She lives in Clonoe, Co Tyrone and has two children.
Ms O'Neill says her new role is "a huge honour, a really big, big privilege" and paid tribute to the work of Mr McGuinness over the past ten years.
“It has absolutely been my privilege to work so closely with Martin over the last ten years," she said.
“To always learn from him and be inspired by him; how he conducts himself in all situations is a lesson to each and every one of us. How he reached out and broke down barriers is a testament to the genuine nature of the man that he is."
The Minister for Foreign Affairs, Charlie Flanagan congratulated Ms O'Neill following the announcement adding that the government is looking forward to working closely with her in her new role.
"I know that we share a sense of urgency in our determination to see the power-sharing institutions effectively functioning at Stormont once the election has taken place," He said.
"A key shared objective will be to work, together with the other political parties in Northern Ireland, to ensure that the full promise of the Good Friday Agreement and successor agreements are realised.
"This includes the prompt re-establishment of the devolved institutions, underpinned by genuine partnership and equality, following the current election campaign."