Moulton School and Science College will see 30 extra school places a year from September 2017 to cope with growing pupil numbers.
Northamptonshire County Council, which has the statutory duty for ensuring sufficient school places, is working with education providers to expand the number of pupils at the school, and also increase the admission number for Corby Technical School by 75 pupils.
The move will increase the admission number at Moulton School to 270 per year.
Plans will also be discussed at a cabinet meeting next week (Tuesday, April 19) to increase capacity at a number of special schools in Northamptonshire.
It is proposed to increase the capacity at Isebrook in Kettering (75 places), Friars in Wellingborough (12 places), Wren Spinney in Kettering (12 places), Billing Brook in Northampton (eight places) and Fairfields in Northampton (eight places).
Cllr Matthew Golby, county council cabinet member for learning, skills and education, said: “The number of children entering Northamptonshire primary schools has risen by 11.5 per cent in the last five years and as those children move through primary education, there is a need to create new secondary school places to cope with the increase in pupil numbers.
“We are working closely with the Brooke Weston Trust in Corby and with Moulton School and Science College, which are both academies, to provide the extra places the two schools require, as well as looking further head to plan for future demand in these areas and across Northamptonshire.”
The new places at Corby Technical School and Moulton School and Science College will be funded through Department for Education grants, school contributions and Section 106 developer funds.
As both are academies, the expansion at Corby Technical School will be subject to formal approval by the Brooke Weston Trust and the expansion at Moulton School and Science College will be determined by the governing body.
However, the county council is responsible for identifying funding for expansions at academies to accommodate growth in pupil numbers due to demographic pressures.
These two projects are being funded by Department for Education grants and Section 106 developer contributions.
Additional new secondary schools will be needed in both Corby and Northampton by 2018/19 to cope with rising pupil numbers and the county council is currently working with the Education Funding Agency to identify suitable sites and secure capital funding for the two new free schools.