It will be mandatory for pupils to wear face masks in communal areas of secondary schools in England in places with local lockdowns, Britain's education minister Gavin Williamson said.
It comes after a government U-turn on enforcing their use in places facing restrictions to curb the spread of COVID-19.
Headteachers in other areas will also have the discretion to recommend using masks in their schools for students aged between 11 and 18.
"There are some areas of the country where we have had to do local lockdowns and we think it is right in those few areas that in secondary schools, in communal areas, that youngsters do wear face coverings," Williamson told Sky News.
It is the latest U-turn by the British Prime Minister Boris Johnson's government which has come under fire for its handling of the pandemic and is under pressure to ensure all England's pupils return to school after a debacle over exam grades earlier this month.
The new policy on masks also marks the latest occasion when Johnson has followed the devolved Scottish government in revising pandemic rules, after changes to the grading of exams and enforcing face coverings in shops.
Huw Merriman, chairman of parliament's transport select committee and a member of Johnson's party, said it felt like the government was making it up as it went along.
"It's time we stopped hiding behind the science, which keeps changing, and we focus on the fact that we are in charge," he told BBC Radio.
Williamson, who apologised after an algorithm-based exam system saw swathes of pupils awarded lower-than-expected grades, said the shift on masks had come following the change in WHO advice.