Anyone owning a drone that weighs more than 250g (8.8oz) will be legally required to register it and could face a £1,000 fine if they fail to do so and are caught flying it.
The legislation is aimed at tackling drone misuse and the rising number of incidents that aviation authorities have had to deal with in recent years.
There were 125 incidents last year and 87 reported so far in 2019.
In a statement, the Civil Aviation Authority (CAA) said: “UK drone laws are changing and it’s vital that drone users – whether they fly regularly or not – are aware of how the drone registration scheme will affect them.”
A rogue drone caused chaos at Gatwick Airport last December with 1,000 flights cancelled or diverted, affecting 140,000 passengers over two days.
The drone responsible, and its operator, was never found.
The CAA has revealed that just 40,000 of the UK’s estimated 90,000 drone owners have registered their devices since the system was launched earlier this month.
Its website crashed on Friday due to the high volume of owners trying to register their drones.
Retailers across the country are now bracing themselves for questions about the new regulations from would-be drone owners in the run-up to Christmas.
“For us it’s very much going to be a case of making sure that customers are aware of the new regulations,” said Danny Roe, manager of gadget and technology shop Menkind in Kingston-upon-Thames.
“We have leaflets on the counter too.
“I think some customers will be confused by it, but it’s up to us as retailers to inform them.
“Our drones range in price from £25 up to £250 and we have at least two models which will be affected by the new rules.
“At this time of the year there is always a real ‘wow’ factor to drones, they fly off the shelves in the run up to Christmas.”
In the aftermath of the Gatwick Airport drone incident the no-fly zone around airports was extended in March from 0.6 miles (1km) to 3.1 miles (5km).