Wicklow County Council is to borrow €9 million to buy the former private school, Our Lady's College near Rathnew, in a joint venture with property developer Ardan plc.
The council is hoping to develop a third-level institute in association with Carlow Institute of Technology.
Explaining the deal to councillors yesterday, county manager Eddie Sheehy said the council had initially tried to buy the entire college on its own behalf but could not afford the purchase price of more than €15 million plus stamp duty.
Mr Sheehy said Pat Shine, Bill Mulrooney and Brendan Fitzsimons of Ardan plc, who had developed an 800-house and town-centre development in Blessington, were then brought in as joint venture partners to put in a bid.
Mr Sheehy said Wicklow was one of the few counties without a third-level education facility and the Department of Education had already refused to buy Our Lady's College to develop third-level courses there.
The council was left with the choice of doing nothing or taking a proactive role and had chosen the latter, he said. Details of the deal remain to be finalised between the council and Ardan.
But Mr Sheehy said a division of the lands giving the council the college and educational buildings, Ardan a three-acre site zoned town centre, and joint development of the remaining site, was one of the options under consideration. Alternatively, the council and Ardan could hold the entire site jointly.
Following formal approval from the councillors to raise a loan to buy the property yesterday, Mr Sheehy will now seek another consent from the Department of the Environment, although he said he believed he had the support of Minister for the Environment Dick Roche for the project.
Contracts for the purchase would be exchanged "in a couple of days", Mr Sheehy said.