Taoiseach Micheál Martin has laid a laurel wreath at the war memorial in Enniskillen as part of Remembrance Sunday events taking place across the UK.
The ceremony in the Co Fermanagh town also remembers the 12 people killed in an IRA bomb attack on the Remembrance event there in 1987.
Mr Martin stood alongside Northern Ireland Secretary of State Hilary Benn as a two-minute silence was observed at 11am.
In Belfast, Sinn Féin deputy leader and Stormont's First Minister Michelle O’Neill laid a laurel wreath at the Cenotaph for the second successive year.
In a poster on X, she said that as First Minister it was her responsibility "to acknowledge and show respect for all traditions and perspectives in our society".
She was joined by Deputy First Minister Emma Little Pengelly, who also laid a wreath.
The DUP politician has said she had to decline an invitation to attend the inauguration of president-elect Catherine Connolly on Tuesday because of prior arrangements to attend Remembrance Day events.
King Charles leads Britain's commemorations
Meanwhile, Britain's King Charles led the commemorations in the UK, honouring those who have died in conflict, at a ceremony attended by thousands of veterans.
King Charles took centre stage and laid the first wreath at the Cenotaph in recognition of the fallen from conflicts dating back to the First World War, and was followed by the Prince of Wales.
The King, wearing Field Marshal uniform with a ceremonial frock coat, saluted before stepping back from the monument after leading a two-minute silence at the annual Remembrance Sunday service in London.
His son, dressed in Royal Air Force uniform in the rank of Wing Commander, also saluted after laying his wreath at the Cenotaph.
Prince William, who in 2013 completed seven and a half years of full-time operational military service, promotes the roles and welfare of current and former service personnel as a key part of his work.
British Prime Minister Keir Starmer also laid a floral tribute, along with senior politicians including Kemi Badenoch, Ed Davey, Yvette Cooper, Shabana Mahmood and Lindsay Hoyle and representatives from the Commonwealth.
The Princess of Wales Kate Middleton and Queen Camilla, both dressed in black, and other members of the royal family viewed the Remembrance Sunday service from a balcony at the Foreign, Commonwealth & Development Office in London overlooking the Cenotaph.
