She said the change – from February 28 when all schools have returned from the half-term break – is a “further step in allowing children and young people a return to a more normal experience in school after many, many months of sacrifice”.
Face coverings will still be required in other communal, indoor areas within high schools, the First Minister confirmed, but this will be kept under “regular review”.
The announcement came 24 hours after Prime Minister Boris Johnson announced the last domestic restrictions in England, including the legal requirement to self-isolate if you test positive, are likely to be lifted later this month, “a full month early”.
Ms Sturgeon said the requirement for face coverings in classrooms was being relaxed following the latest advice from an expert group, who considered the matter on Tuesday.
Announcing the change at the start of First Minister’s Questions at Holyrood, Ms Sturgeon said the move would “reduce barriers to communication in the classroom and reduce any wellbeing impacts which arise from the use of face coverings”.
It is made possible by “reducing case rates” for coronavirus in secondary school-aged children, she said, as well as the decrease in hospital admission rates among all ages.
This “encouraging situation” also means restrictions on school assemblies can be lifted, along with those on transition visits for youngsters either starting primary or secondary school, the First Minister added.
While the guidance will be updated next week, Ms Sturgeon said she had wanted to confirm the change as soon as possible “to give children and young people, their families and school staff certainty about the forthcoming changes before the February break”.
The Scottish Conservatives have pressed ministers on the issue for weeks, with party leader Douglas Ross saying: “Young people’s education has been unnecessarily disrupted for far too long.”
He added: “Finally, after weeks of refusing to budge, the Government has U-turned.
“While it is welcome, it has taken much longer than was necessary.”
Ms Sturgeon insisted: “Had we done it before today, we would have been acting against expert and scientific advice – it would have been the wrong thing to do.
“We are doing it now at the right time and in line with advice and I think that marks the responsibility of this Government in contrast with the irresponsibility of the main opposition.”
Scottish Labour leader Anas Sarwar also welcomed the move, but said “after almost two years, this will add anxiety for staff and workers in schools as well as for parents”.
He said it made the need for ventilation and air filters in classrooms “more crucial”, insisting: “We need a credible plan from the Government on those issues.”
Scottish Liberal Democrat education spokesman Willie Rennie said the move would be “a source of anxiety” for some pupils and teachers.
The Lib Dem added: “We need proper ventilation in every classroom.
“The First Minister should announce fresh financial support so that schools can install air filters in every classroom, tackle Covid build-up and make our schools safer for pupils and staff alike.
“This will help not just with Omicron, but with future outbreaks and education performance more generally.”
Larry Flanagan, general secretary of the EIS teaching union, said most of its members would have preferred to wait until spring before ditching masks in classes.
Mr Flanagan said: “The majority of EIS members supported the retention of face coverings until we were through the winter period so we would have preferred the end of March rather than the end of February for this change to happen.
“Having said that, it is important that both pupils and staff have the right to continue to wear face coverings if they wish and, in some cases, where there is a heightened vulnerability in play, face coverings may still be required.
“There has been a slight drop in infection levels within schools, but they remain high. Over 4,000 staff are off school for Covid-related reasons and more than 20,000 pupils. Enforcing the remaining mitigations, therefore, around ventilation and face coverings in communal areas, remains critical to school safety.”
Meanwhile, the latest figures show Scotland recorded 24 coronavirus-linked deaths and 7,275 new cases in the 24 hours to Thursday.
The Scottish Government data means the total number of people who have died within 28 days of testing positive for Covid-19 has risen to 10,485.
The daily figures have included lateral flow test results since January 6 following a change to testing policy.
There were 904 people in hospital on Wednesday with recently confirmed Covid, down 30 on the previous day, with 19 in intensive care, down two.
So far, 4,424,596 people have received their first dose of a Covid-19 vaccination, 4,139,618 have had a second dose, and 3,332,960 have received a third dose or booster.