The study, conducted by the University of KwaZulu-Natal, found that violence had become synonymous with respect and a sense of belonging among pupils in Grades 9 to 11 at the school, which was not named.
A fifth could see themselves joining a gang.
Boys exhibited a greater inclination for violence, with 16% agreeing that they could see themselves committing a violent crime in the next five years, compared to 12% of girls.
About 28% of pupils had a "positive" attitude towards violence.
"The assumption that public schools are the domain of violence is incorrect," said criminology lecturer Nirmala Gopal, who conducted the research among 100 pupils at the school.
The teenagers were asked to respond to statements such as, "I could see myself committing a violent crime in five years", and "Parents should tell their children to use violence if necessary".