The London District Catholic School Board (LDCSB) says the Middlesex-London Health Unit has identified a coronavirus case at Catholic Central High School (CCH) Tuesday night.
The school board says CCH will remain open and school buses will continue to operate.
They say the health unit is currently identifying close contacts.
Tuesday marks at least the seventh day in a row for a school-linked case to be reported in the London and Middlesex region.
Cases remain active at at least seven schools and two daycare centres.
The region has seen a total of 32 COVID-19 cases linked to schools.