More than half of children leaving care were 16
Many young people are being "pushed out" of the care system before they are ready, according to a report.
The commissioner for children, Kathleen Marshall, found that more than half the children who left care last year were aged 16.
She said this could leave them vulnerable to homelessness, drink and drugs problems and unemployment.
The Scottish Government said children should remain in care until 18 if it is in their best interests.
Ms Marshall claimed that, in many cases, children were being seen as a "troublesome burden" rather than "a vulnerable person to be nurtured, cared for and listened to".
She added: "At just 16 years old - the very time that they need help to cope, adjust and find their place in the world - many are all but completely abandoned with little, if any, aftercare."
The commissioner warned that leaving care early could bring children into "highly inappropriate settings" such as bed and breakfast accommodation or homeless hostels.
Her report - entitled "Sweet 16?" - claimed that one young person was put in a bed and breakfast accommodation where a convicted murderer was a fellow guest.
She added: "We need the message to be heard loud and clear - sixteen is not the age of leaving care in Scotland."
The report made 23 recommendations, including a call for "strong action" to change the culture that assumes 16 is the age for leaving care.
It also recommended workers be trained and informed about young people's rights, so they can pass this information on to youngsters.
The report also called for more semi-independent living units to be provided and for a ban on the use of bed and breakfast accommodation and homeless hostels to house those leaving care.
Tam Baillie, of the charity Barnardo's Scotland, said: "We need to ask ourselves why our most vulnerable young people are expected to be fully independent at such a young age, often in very difficult circumstances."
A spokesman for the Scottish Government said: "We are committed to helping children in care develop into self-confident, successful adults and agree that more needs to be done to help them make the transition to independent living."
He said the government was working with councils to make sure that care leavers were appropriately housed.
Figures showed that in 2007 there were more than 14,000 children in care - 26% more than in 1999 and the highest number since 1982.