"The Trash", billed as an all-star punk revival big band, features the musical talents of a range of staff and others with links to the school.
It will perform on the last day of term next month.
The band was created as part of the SOHS art week, which finished yesterday, but it will live on with a one-song performance during the lunchtime assembly on Friday, July 3.
Teacher and unofficial band manager Glenys Whittington said the band included principal Nick Simpson, teachers, support staff , a board of trustees member and one of the grounds staff.
The band has been rehearsing when possible.
"It's a bit tricky trying to get more than 20 staff and others together at the same time," Ms Whittington said.
Forming the band was in keeping with a new curriculum directive from the Ministry of Education, which encouraged "contributing and participating".
Ms Whittington said, tongue firmly in cheek, the band would gauge the response to its one-off show before it considered taking the group "on the road".
Details of the band's one-off show, featuring just the one song, are being kept under wraps.