In the "dark days" of Northern Ireland's troubles, former SDLP leader, Mr John Hume, represented the voice of "reason, common sense and compassion", the Taoiseach, Mr Ahern, said today.
Mr Hume this afternoon announced his intention not to stand next June's European Parliament election - effectively completing his gradual retirement from Irish political life.
Mr Ahern today praised Mr Hume's foresight for recognising many years ago the potential of the European Union as a model for achieving peace in the North.
"Through his tireless and eloquent advocacy, he persuaded us all of the inspiring relevance of the European experience - how working together on the common problems that unite us can transcend the difficult issues that divide us."
Mr Hume's insistence on peace as the only way for Irish nationalism to achieve its goals had a significant influence on British governments leading to the current "inclusive political process", Mr Ahern said.
"John Hume can be immensely proud of his record and achievements in Europe and at Westminster, for which he has earned the respect and gratitude of the people of Ireland."
European Parliament president Mr Pat Cox paid tribute to Mr Hume as an outstanding politician. Mr Cox said he was an effective voice throughout Europe for peace in Northern Ireland.
"He is one of the European Parliament's most outstanding, respected and longest serving members. His dogged commitment to non-violent conflict resolution has been steadfast and constant.
"He realised that international engagement was essential to break the inertia of insular isolation. His conviction that difference is not a threat but the essence of humanity is a message that has carried throughout Europe and beyond," said Mr Cox.
Labour MEP for Dublin, Proinsias De Rossa paid tribute to Mr Hume for the "enormous contribution he has made to public life in Ireland, at European and international level over the past 30 years".
"I know that John was always inspired by the post-war reconciliation that occurred between France and Germany in the context of building the European Union and constantly sought to apply the fundamental principle of European integration - the principle of consent based on mutual respect - to Northern Ireland.
"I have been privileged to work with John in the European Socialist Group where he used every opportunity to press home the lessons learnt regarding conflict prevention and reconciliation."