Caerphilly councillors came to the decision at a specially convened meeting, a week after the asbestos was discovered at Cwmcarn High School.
Pupils will move to Coleg Gwent's campus in Ebbw Vale while the issue is resolved, starting on Monday, 5 November. The move will cost up to £1.4m.
The school was shut on Friday, 15 October after a structural report identified asbestos in the main block.
The discovery of the asbestos, prompted unions to call on Westminster for a national asbestos audit of UK schools, following the lead of the welsh government.
Wales' Education Minister Leighton Andrews has asked all local authorities in Wales for reassurances about the asbestos in their schools.
Despite Westminster's claims to be working with the Health and Safety Executive (HSE) on schools' asbestos management, HSE no longer proactively inspects UK schools.
Over 75% of Britain's state schools contain asbestos, according to the Asbestos in Schools: the need for action report by the All-Party Parliamentary Group on Occupational Safety and Health.
Furthermore, the report revealed that much of the asbestos is badly maintained. More than 140 school teachers have died from mesothelioma (a cancer that is almost exclusively caused by exposure to asbestos) in the past 10 years.