Producing or selling them could carry a prison sentence of up to seven years under new laws announced today.
Ministers have also announced that police will be given the power to shut down websites which sell them in a range of new plans to tackle the growing problem.
Legal highs include nitrous oxide - also known as laughing gas, incense, salts and plant food.
They are often very similar to illegal drugs but cannot currently be banned because they are marked not for human consumption.
The new law will it will be an offence to produce, supply, offer to supply, possess with intent to supply, import or export psychoactive substances or legal highs.
Speaking on Premier's News Hour Marolin Watson from Christian drugs charity Hope UK welcomed the change: "The government has banned various substances but as soon as one is banned, two more take their place, with slightly different chemical compositions.
"You do worry that especially children and young people would tend to equate legal with safe."
She added that the seven year sentence "seemed quite reasonable" and that it would "hopefully act as a deterrent".
A number of young people have died in recent years after taking legal highs.
In 2012, 17-year-old Joseph Bennett suffered a cardiac arrest after taking nitrous oxide, also known as laughing gas.
Commander Simon Bray, the National Police Chiefs' Council lead for new psychoactive substances, said: "When people buy dangerous drugs they will generally have little idea how potent the drug is or what it may contain.
"Sadly we have seen too many people losing their lives or becoming seriously ill after taking so-called 'legal highs' under the impression that they are safe.
"A blanket ban on new psychoactive substances (NPS) will make it simpler for law enforcement to deal with those drugs which are potentially unsafe but which may not yet be controlled."
Marolin Watson speaking to Premier's Hannah Tooley:
