The Torbay and South Devon Trust's mental health service is unsafe, independent ratings show.
This comes after the Government announced reforms to the "outdated" Mental Health Act to improve support and treatment of patients and address disparities.
The Care Quality Commission independently monitors the quality and safety of health and social care services across the country.
Its data shows the safety of mental health services across England remains concerning, with 40% rated as 'requires improvement' or 'inadequate'.
Torbay and South Devon NHS Foundation Trust's specialist community mental health services for children and young people were rated as 'requires improvement' when it was assessed.
Health Secretary Wes Streeting said: "Our outdated mental health system is letting down some of the most vulnerable people in our society, and is in urgent need of reform."
"By bringing the Mental Health Act in line with the 21st century, we will make sure patients are treated with dignity and respect and the public are kept safe," he added.
Chris Dzikiti, interim chief inspector of healthcare at CQC, said the commission raised concerns about children and young people’s mental health services in its annual state of care report.
The report also highlighted the lack of resources, ageing estates and poorly designed facilities affecting patient safety on mental health wards.
"Where we find that people are at risk of harm, we can and do take action to protect them and to drive improvement," he added.
"But there also needs to be targeted funding, improved community support and investment in the workforce to make sure that people with mental health needs get the right care, in the right place, at the right time."
An NHS spokesperson said: "We know that mental health services across the country are under real pressure, and we are working hard to support them and reduce waiting times for patients.
"This includes boosting community services so we can intervene earlier with hundreds of NHS teams working in schools and trialling new 24/7 open access mental health centres to prevent people needing hospital care in the first place.
"When an admission to hospital is needed, the NHS is working with local services to ensure this is delivered in a safe and therapeutic environment close to people’s homes."