Lancashire County Council's cabinet has agreed to expand Unity College in Burnley to meet the demand for places following the closure of Hameldon Community College.
The Cabinet agreed to approve a permanent expansion of 30 pupil places each year from September 2021 at Unity College, in addition to the permanent expansion of 30 extra places each year from September 2020, as agreed in August.
An extra 150 places at the school will be created in total within five years.
Councillors rescinded the decision, made by Cabinet in August, approving a permanent expansion of 30 places each year at Shuttleworth College in Padiham. There will instead be a temporary increase of 30 pupil places at Shuttleworth for September 2020 only.
It was decided not to permanently expand Shuttleworth following an investigation of five potential locations at the site.
Three of the sites considered are affected by the possible presence of protected species which would delay the programme past the date that the places are needed by. The other two locations are affected by historic mine workings.
At today's meeting, the Cabinet also approved the expenditure for the permanent expansion of Unity.
The county council's Easden Clough site in Morse Street will be used for the extra pupils, subject to relevant permissions being obtained, and work taking place to provide suitable facilities for education.
The expansion at Unity College, at Towneley Holmes, will increase the number of Year 7 places from 240 to 270 in 2020 and a further 30 in 2021
The extra places that were needed for September 2019 have been provided temporarily by both schools taking on the additional pupils.
County Councillor Phillippa Williamson, Cabinet Member for children, young people and schools, said: "The county council is responsible for making sure that there are enough school places to meet the demand.
"We are constantly reviewing changing demographic factors to make sure that we have the right number of school places throughout the county, and we knew that there was a need for some additional secondary places in this part of the county.
"Unity College will provide the extra places that are needed permanently."