Around 700 rioters, convicted of a range of charges including violent crimes, burglary, theft and arson, have been released from prison.
The disclosure has led to fears the convicted rioters will be free to take part in any future violent action, with one Tory MP saying people would be "rightly outraged".
The rioters, many of whom were teenagers, each took part in public disturbances throughout Britain in August 2011, with many causing havoc on the streets of London.
At the time, judges handed down harsh sentences as a deterrent to troublemakers.
According to official statistics, 1,968 people were sentenced for their involvement in the riots, with 1,292 of them being jailed following the violence.
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The average sentence for those jailed by magistrates was six-and-a-half months, with those sentenced in Crown Courts reaching 19.4 months.
Each could be released from prison half way through their sentences, in line with normal national guidelines.
Another 676 were given fines, community services, suspended sentences or had their crimes discharged.
By the middle of June, only 692 remained in jail for their part in the disorder, with dozens more likely to have been released since, according to the Daily Mail.
Tory MP Andrew Percy told the Daily Mail: "People will be rightly outraged that so many are out so soon, even before the first anniversary.
"The fear will be that they may revisit their crimes this summer."
A Ministry of Justice spokesman said: "The courts, judges, probation and prison services worked hard to ensure that those who attacked their communities faced justice quickly.
"This was crucial in stopping the riots spreading further by delivering swift and sure justice.
"The message is clear: the disgraceful behaviour that innocent communities endured last summer will not be tolerated."
In August last year, Prime Minister David Cameron said: "I think it's right that we should allow the courts to make decisions about sentencing.
"They decided in that court to send a tough sentence, send a tough message and I think it's very good that courts are able to do that."