Contractors have been appointed to oversee the construction of £22 million replacement for Brecon High School.
Powys council has appointed BAM UK Construct Ltd to lead the project which will see the existing secondary school replaced with new school buildings.
The council said the appointment is a major step forward for the project.
Powys council’s acting head of schools Gareth Jones said: "Appointing a contractor means we will be able progress design and build plans and we look forward to working closely with the school and the community."
Powys council first unveiled plans to rebuild the Penlan high school in March 2013 but its initial proposals failed to win the support of the Welsh Government.
It later revived the plans and proposed creating a new 11 to 16 school at the site, to replace both Brecon and Gwernyfed high schools, but dropped that plan last September following a public backlash.
The council’s outline business case for the construction of the new 11-18 school in Brecon, to replace the current school buildings was approved last autumn as part of the Welsh Government’s 21st Century Schools and Education Programme.
David Meredith, chair of governors at Brecon High School said: "We are very pleased that the tender process has concluded with the successful appointment of an experienced contractor for what is a major project for the school and the next step in the schools journey of success following the examination success last summer and the school being removed from special measures."
The county council said it has recognised the need to improve the secondary school infrastructure for some time and the replacement school is a key part of plans to ensure pupils in the Brecon community are taught in buildings that are fit for purpose.