In April the union raised concerns about the government's plan to sell the training college in the Cotswolds – which was in danger of being closed – to a private owner.
Negotiator Philippa Childs said: "We hope today's news will provide job security for staff and end the uncertainty that has been facing them since the sale was formally announced by the Department for Communities and Local Government.
"Consultation with the new owner on the transfer will begin next week and Prospect intends to work closely with Capita to ensure the organisation's long-term viability as a world-class training facility.
"While we are disappointed that the college could not remain as a trading fund within the public sector, government spending cuts meant that no money could be spent on the infrastructure, recruitment or pay rises. We hope today's announcement signals light at the end of the tunnel."
The college, where Prospect represents more than 70 lecturers and other staff, is an award-winning leader in fire and emergency response training and one of the largest operational fire and rescue training colleges worldwide.