Leo Varadkar has chosen his beaten rival in the recent Fine Gael leadership contest as his deputy.
Minister for Housing Simon Coveney will take up the role.
Mr Varadkar is expected to be elected as taoiseach tomorrow afternoon.
Mr Varadkar said: "Simon and I will work together to guide the participation by Fine Gael in the Government, and reform and modernise the Fine Gael party in the years ahead."
Mr Coveney said: "I am honoured to have been asked to take on the role of deputy leader of Fine Gael. I will ensure this is an active role which reaches out to the members of the Party across the country.
"I look forward to working with the new leader of Fine Gael, Leo Varadkar, and believe that I can bring a strong focus and energy to the party from the grassroots members through to local councillors, and up to the parliamentary party. This is an exciting new chapter for the party and I intend to play a strong role in it."
The news comes as Mr Varadkar addressed the first meeting of the parliamentary Fine Gael party since his election as leader.
The taoiseach-in-waiting updated Fine Gael members on his discussions with the Independent Alliance, independent TDs, and Fianna Fáil.