The Taoiseach sent his congratulations to Mr David Trimble and Mr Mark Durkan within minutes of their election as First and Deputy First Minister in Northern Ireland.
Mr Ahern also applauded the efforts of the pro-Agreement political parties in "coming together to ensure that the challenge to the agreement was successfully addressed".
Mr Ahern underscored the importance of now moving ahead with the Agreement's full implementation.
In a clear reference to the tactics of anti-agreement Ulster Unionists and the Democratic Unionists, Mr Ahern said: "Those who are determined to pursue the failed politics of the past will not succeed.
"They should know that time has move on and there is no going back. Stable, uninterrupted and inclusive government is essential for Northern Ireland" .
Mr Ahern said he looked forward to continuing co-operation with Mr Trimble and Mr Durkan and the other members of the executive.
He also paid tribute to SDLP deputy leader Mr Seamus Mallon, who stood down as deputy first minister.
PA