An investigation by HM Inspectorate of Probation and HM Inspectorate of Prisons found a fifth of young people released from young offender institutions were convicted of a further offence within three months of release.
The report, which followed the experiences of 50 boys aged 12 to 17 detained in institutions across England and Wales, outlines a series of recommendations to government departments and agencies to improve the support provided to young offenders after release.
Its findings revealed there was inadequate support for helping these young people find accommodation, with some being told where they would be living just days before release.
It also found support for substance misuse was only delivered in 44 per cent of cases after release. This was despite substance misuse being identified in three quarters of cases in the study.
- Analysis: Draft standards miss the mark
- Analysis: Tougher inspections for STCs
- Analysis: Five steps to good resettlement
Similarly, young people's mental health issues were not properly considered once they were back in the community.
"Good work in mental health support during custody was often negated by a lack of attention to continuing support on release," the report states.
Furthermore, a lack of support for education, training or employment "rarely led to purposeful activity in the community, or contributed to helping the child consider, meaningfully, his future possibilities", it adds.
The findings, which relate to the period from October 2018 to April 2019, show 37 out of 50 young offenders needed help from children's social care services, but only six of these received help with resettlement.
Only 11 of these young people went into education or training after release.
Inspectors said the second half the sentence being served by the group in the community often did not build on or "ignored" what had taken place in custody.
They reported "poor" criminal justice outcomes for the cohort three months after release with 10 convicted of a further offence and more than half under police investigation. Six of the group were reported missing.
The report follows an interim investigation carried out in August which revealed frequent examples of inadequate planning.
Chief inspector of prisons Peter Clarke, said in some cases planning started just 10 days before release or even after young people had been released.
"This is too little, too late to be effective. A lot of the activity that we saw in custody focused on containing children and young people, managing their behaviour or simply trying to fill their time."
Chief inspector of probation Justin Russell said it was "immensely disappointing" to find many of the same issues remained from a report the inspectorate published on youth resettlement in 2015.
He called for a national network of community-based accommodation for children who posed the highest risks to the public and better co-ordination between staff in custody and in the community to ensure help was given to young people to "plan, prepare and thrive" after release.
"This is not just in the individual's interests. Their families, communities and society as a whole stand to gain from people living crime-free lives," he said.