Explorers, at Sundorne, has remained open throughout the pandemic, caring for children of key workers, vulnerable youngsters and children with additional needs from around the town.
But the nursery has had to close this week due to a positive case of the virus, and staff and children are self-isolating.
The nursery confirmed the case in a statement, and thanked colleagues, parents and carers for their support.
It said: "We have had to close due to a case of Covid. We would like to take this opportunity to send our very best wishes to the staff member who is unwell.
"Thank you to all parents/carers for their continued support."