In an interview with CYP Now, the newly-appointed shadow education secretary said provision for young people should have been better, and that their needs were not fully understood.
"It has been a neglected service down the years on both the health and educational side - let's be clear about that," he said.
Burnham added that the neglect was due to badly thought-out services that focused too much on adult's needs. "Young people often end up using adult services that can be disorientating and overwhelming," he said. "It's something I heard a lot as Health Secretary."
A review of NHS services for children and young people by Professor Sir Ian Kennedy was published in September. It found young people were often distressed by the treatment received through CAMHS and called for an urgent response to children and young people's mental health needs.
Lucie Russell, YoungMinds' campaigns director, said: "Under the previous government some good policy measures were introduced to child and adolescent mental health services. Unfortunately, these measures did not translate into improvements and CAMHS remains the Cinderella of Cinderella services."
She added that Burnham needed to hold the coalition to account to ensure the thousands of young people receiving mental health services get the treatment they need.