In a letter sent to parents, Smestow School said they had identified year 11 pupils could have been in close contact with one of the positive cases.
The letter, which has been seen by the Express and Star, said: "We have been made aware that we have a confirmed positive case of coronavirus (Covid-19) at Smestow School.
"We have followed the national guidance and have identified that year 11 could have been in close contact with the affected child. In line with national guidance, your child must stay at home and self-isolate until Friday, October 30.
"If your child is well at the end of the 14 days period of self-isolation, then they can return to usual activities."
A spokesman for Smestow School said: "We can confirm that we have two Covid confirmed cases.
"As soon as we were aware we took advice, as directed, through the Department for Education. In all circumstances the national guidance has been implemented and this was recognised in our recent Ofsted Covid visit.
"We continue to put the health and safety of staff at the front of all our decisions."