Dutch NGO KidsRights said schools for more than 168 million children have been closed for almost a full year, with one in three children worldwide unable to access remote learning while their schools were shut.
An additional 142 million kids fell into material poverty as the global economy was hit by the pandemic, while 370 million kids missed out on school meals.
KidsRights paid tribute to Manchester United and England footballer Marcus Rashford for his campaign to extend free school meals.
It also hailed Bangladesh for taking over a national TV channel for homeschooling and praised Belgium and Sweden for trying to keep schools open.
Meanwhile, 80 million children under the age of one could miss out on routine vaccination for other diseases because of disruption to healthcare systems, it said.
The report said there was also an “astonishing increase” in domestic violence during lockdowns, with children often the victims.