The Green Party has voted to go into government with Fine Gael and Fianna Fáil.
It clears the way for the Fianna Fáil / Fine Gael / Greens government to be formed, after the other two parties also backed the deal earlier on Friday.
Fianna Fáil leader Micheál Martin is now expected to be elected as Taoiseach by the Dáil tomorrow.
The Greens had needed a two-thirds majority of members to approve the deal in a postal ballot.
Almost 1,900 members of the party cast their votes - with the final result 76% to 24% for no.
Speaking after the vote, Green leader Eamon Ryan pledged to work with their coalition partners to "set our country on this new future... one that's sustainable in every way: socially, economically and environmentally."
Deputy leader Catherine Martin said members could be reassured that the party will "work every day to ensure this government will deliver for all the people of Ireland".
She said it wouldn't be easy, but added they intend to "hit the ground running".
Deputy Martin acknowledged that many members will be sceptical of going into government with Fine Gael and Fianna Fáil, but suggested that people in those parties also "may not be overjoyed" about working with the Greens.
Fine Gael / Fianna Fáil votes
It was earlier confirmed that members of Fine Gael had backed the deal overwhelmingly, with 80% voting yes and 20% voting no.
There was also strong support for the deal with Fianna Fáil, with 74% of their members voting in favour of the deal.
Speaking after his party's vote, Micheál Martin said it was an important day for his party.
He said he didn't "understate the gravity of the situation" facing the country.
However, he noted: "I think it's a moment of opportunity, and a moment of hope for our people - that we face up to the challenges, overcome them, and lead to a better type of society."
Special Dáil sitting
With the programme for government now approved by the individual parties, the Dáil will hold a special sitting at the Convention Centre Dublin tomorrow to elect a new Taoiseach.
Under the coalition deal, Deputy Martin will hold the role until December 2022, with Leo Varadkar to take over then for the remainder of the new government's term.
If approved, Micheál Martin will tomorrow also appoint his Cabinet ministers.
Sources have also said it looks as though Fine Gael will keep the Foreign Affairs, Finance, Business and Justice portfolios, while Fianna Fáil will take charge of Housing and Public Expenditure, and possibly Education.
Green leader Eamon Ryan is expected to take charge of a new Climate and Transport Department.
Micheál Martin has confirmed that the role of Attorney General will also rotate between Fine Gael and Fianna Fáil.
