0734 GMT January 16, 2022
Thousands of armed police and troops patrolled the camps in the Cox's Bazar district but did not act against the children, according to AFP.
More than 700,000 Muslim Rohingya, who have long been persecuted in Buddhist-majority Myanmar, fled into Bangladesh after the 2017 clampdown which is the subject of a genocide investigation by the International Criminal Court.
Children as young as five took part in the surprise 15-minute march in the Kutupalong camp – the world's largest refugee settlement – to demand justice for the thousands of Rohingya reported killed in the crackdown.
Community leader Mohammad Osman said between 3,000 and 4,000 children took part, chanting "we want justice" and "we want safe repatriation". Police said only a few dozen children were involved.
Some women also staged silent protests in front of their shanty homes holding placards that read "we want justice", a rights activist said.
Journalists were not allowed into the camps for the anniversary.
Bangladesh authorities have banned protests and rallies, saying they could spread the coronavirus. The pandemic has killed at least 30 Rohingya and infected thousands.
Daily infection numbers have fallen recently and the government has eased national restrictions but would not allow the Rohingya to stage even small events Wednesday.
In Myanmar, where hundreds of thousands more Rohingya also live in camps, several groups issued statements calling for faster efforts to prosecute perpetrators of the 2017 military action.