A new law will also target those using drones to fly materials into jails.
Last year authorities recorded 250 incidents of new psychoactive substances being thrown over prison walls but until now police have had no power to act against those caught in the act because the drugs themselves are not yet illegal.
Now ministers have signed an order to close the loophole.
From November 10 smugglers who throw anything over prison walls will face arrest, while those found to have smuggled packages could face a custodial sentence of up to two years.
Prisons minister Andrew Selous said: “These ‘lethal highs’ fuel violence in our prisons including brutal assaults on staff and other prisoners. It’s got to stop.
“That is why we’re closing this dangerous loophole in the law so perpetrators will now face up to two years in prison.”
New psychoactive substances can cause violent, unpredictable behaviour and lead to prison assaults, the Ministry of Justice said.
Earlier this year it emerged that the drugs, which mimic the effects of traditional banned substances such as cannabis, are suspected to have played a part in the deaths of at least 19 prisoners.
The Government announced a wider crackdown on legal highs earlier this year, with sellers of the drugs facing up to seven years in prison under a new law.
Ian Bickers, governor of HMP Wandsworth in south-west London, said: “These drugs cause huge problems in prisons, fuelling violence and bad behaviour among prisoners.
“They are frequently smuggled in through packages thrown over the wall. Anything that can be done to crack down on this is very welcome.”
The new offence will also cover the flying of items into prisons by a drone or the landing of the gadget itself within prison grounds, regardless of whether it is transporting contraband.
Earlier this year Eve Richard, a senior analyst at the National Offender Management Service (Noms) intelligence unit, was reported to have described the use of drones to drop items into prisons as an “emerging threat”.