Four new classrooms will be among the development's additions.
A midlands secondary school has been given initial approval for a modular extension.
The Minister for Education, Norma Foley, confirmed the news for Portlaoise College.
The extension will see the addition of four new classrooms, a new science lab and an engineering room.
The Laois Offaly Education and Training Board have developed the proposal and will continue to see it through.
Midlands Event For National Women's Enterprise Day Taking Place Tomorrow
Offaly Councillors Call for 10% Increase in GMA Budget
Strike Action: Sinn Fein Leader Calls On Taoiseach To Intervene
Australian Woman Travels To Midlands In Search Of Irish Family Roots
County Councils Closed Nationwide Amid Major Strike Action
Offaly TD Says Alex Dunne Deserves €30k State Funding
€600m Farm Payment Delays A "Bombshell For Farm Families" - IFA
Emergency Services Attend Offaly Fire