While Mr Kenny has now overtaken John A Costello, several Fianna Fáil leaders have enjoyed significantly longer terms
It is a landmark day for Enda Kenny who officially becomes the longest serving Fine Gael Taoiseach.
His 2,234th day as leader exceeds the record of John A Costello, who served two separate terms as Taoiseach in the 1940s and 50s.
Mr Kenny - who first took office in March 2011 - successfully became the first Fine Gael Taoiseach to be elected for a second consecutive term following last year's general election.
However, he is far from the longest serving head of government the Republic has seen - several Fianna Fáil Taoisigh have served significantly longer terms.
Eamon de Valera's 21-year stint in office was almost double that of the second longest serving Taoiseach, Bertie Ahern.
Enda Kenny has been under pressure to stand down in recent months, with calls for a new leader intensifying over Mr Kenny's handling of the Garda whistleblower scandal in February.
The Taoiseach has indicated he will go at a time of his own choosing, although has insisted he will not lead the party into the next election.
Fine Gael TD Noel Rock yesterday suggested the UK elections process is an 'ideal time' for a fresh party leader to be chosen.