Ministers are to publish draft laws they say are a "landmark" in prohibiting the substances' production, distribution, sale and supply.
Legal highs, officially called new psychoactive substances, have been linked to a number of deaths.
Ministers said young people who took them were "taking exceptional risks with their health".
A blanket ban on legal highs, which are often sold online or on the high street, was in the Conservative Party's election manifesto and featured in the Queen's Speech.
Labour also promised to ban their sale and distribution in its manifesto.
The Psychoactive Substances Bill applied to "any substance intended for human consumption that is capable of producing a psychoactive effect", the government said.
Alcohol, tobacco and caffeine will be excluded, and there are also exemptions for food and medical products, while controlled drugs will continue to be regulated by existing laws.
The new restrictions will also extend to the sale of nitrous oxide - also known as laughing gas or "hippy crack" - for human use.
What are legal highs?
The government said the "legitimate sale" of nitrous oxide, which is also used for food processing, medicinal and industrial purposes, would not be affected.
Home Office minister Mike Penning said the measures would "fundamentally change the way we tackle new psychoactive substances".
They would end the "game of cat and mouse" whereby new drugs appeared on the market more quickly than the government could identify and ban them, he said.
He added: "The blanket ban will give police and other law enforcement agencies greater powers to tackle the reckless trade in psychoactive substances, instead of having to take a substance-by-substance approach."
Legal highs are not controlled under the Misuse of Drugs Act, although individual substances, such as mephedrone, have been outlawed.
The government's proposals would apply throughout the United Kingdom, and would include powers to seize and destroy legal highs and to search people, premises and vehicles.
Civil measures - including prohibition notices and prohibition orders - will also be possible.
Commander Simon Bray, of the National Police Chiefs' Council, said: "A blanket ban on new psychoactive substances will make it simpler for law enforcement to deal with those drugs which are potentially unsafe but which may not yet be controlled."

Observations with Japan's Subaru telescope reveal the likely icy body to be some 15.5 billion km from the Sun - about three times further away than even far-flung Pluto.
Scientists say their initial studies suggest that the object - catalogued as  V774104 - is some 500-1,000km across.
It will need to be tracked over time to learn the shape and extent of its orbit through the Solar System.
The discovery was announced at the 47th annual meeting of the American Astronomical Society's Division for Planetary Sciences, taking place in National Harbor near Washington DC.
The team behind the find is led by Scott Sheppard, from the Carnegie Institution for Science, and Chad Trujillo, from the Gemini Observatory in Hawaii.
They specialise in detecting Solar System outliers.
The previously recognised most distant object is the dwarf planet Eris.
This body, which has a moon, Dysnomia, moves between 5.7 billion km and 14.6 billion km from the Sun.
To put some of these numbers in context: Earth is 149 million km from the Sun, and even the most distant major planet - Neptune - seems close at 4.5 billion km, by these standards.
That said, the Voyager 1 probe is further away - just. The epic robotic explorer has now ventured 20 billion km from home.
The big question is whether V774104 sweeps inwards from its present location, like Eris, or outwards, like the objects known as 2012 VP113 and Sedna.
These bodies are currently slightly closer in than Eris, but investigations of their orbits show they will reach far deeper into space, out to 66 billion km and 140 billion km, respectively.
Models for Solar System formation suggest that such objects were probably not created in these weird, eccentric orbits.
One explanation is that they have been perturbed gravitationally and pulled on to their strange trajectories by a passing planet - perhaps one that was expelled from our Solar System early in its history.
Some scientists even speculate that such objects could have been stolen from a star that formed from the same "nursery" of gas and dust as our Sun 4.6 billion years ago.
Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos
A new "blanket ban" on so-called legal highs will carry prison sentences of up to seven years, the government says.
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Astronomers have identified the most distant object yet in the Solar System.