Hundreds of youngsters have been flagged as being at risk of becoming addicts or have even started abusing alcohol and substances themselves, leading charities to call for improved education in schools.
Freedom of Information requests sent to all councils in England, Wales, Scotland and Northern Ireland reveal children as young as four have been referred to specialists in South Ayrshire.
Eight year olds have been flagged up to services in Waltham Forest and East Ayrshire, while Herefordshire, Liverpool, Oxfordshire, Rutland, the Scottish Borders and West Berkshire have all seen nine year olds referred.
Bury, Calderdale, Halton, Hull, Monmouthshire and Rochdale councils have referred 10 year olds.
The figures were uncovered by the Press Association.
A referral can either mean the child is vulnerable to drug and alcohol misuse through exposure from a parent or relative, or could have started abusing them on their own.
The most common reason for children to come into contact with drugs and alcohol is through their parents, according to experts.
Preventative work is key to heading off the problem among youngsters, they say.
According to the most recent statistics from Public Health England, 366 children aged 12 or under were referred for treatment in 2012/13, compared with 433 in 2011/12.
More than half of under-13s - 59% - received treatment for cannabis misuse.
A third were treated for alcohol misuse, with a small number abusing solvents.
Andrew Brown, director of programmes at the charity Mentor UK, which seeks to protect children from drug and alcohol misuse, said it was "vital" education surrounding alcohol and drugs is improved.
Evidence suggests the "norm" of having one or two lessons on the subject a year is not sufficient, he added.
One of the Government's official drug advisers, Professor Simon Gibbons, recently said more needed to be done on drugs education in primary and middle schools.
By law, schools must cover the harmful effects of drugs on behaviour and health as part of the national science curriculum.
A new curriculum being introduced in September states that pupils in year six - those aged 10 and 11 - must learn to "recognise the impact of diet, exercise and drugs and lifestyle on the way their bodies function".
Personal, Social and Health Education (PSHE) lessons remain non-compulsory, although the Department for Education recommends schools schedule time for them and use the lessons to expand the knowledge pupils get in science lessons.
A Government spokeswoman said: "Both the old and the new curriculum are clear that all pupils should be taught about how drugs and other substances can be harmful to the human body.
"The science curriculum also covers how drugs can affect people's health and lifestyle.
"Teachers are also free to use their professional judgement to address any specific issues that meet the needs of their pupils through PSHE."
