The new EU energy label means manufacturers will not be able to make or import vacuum cleaners with a motor that exceeds 1,600 watts from today, and then 900 watts by 2017.
The Which? consumer group has warned that many of its Best Buy models have motor sizes that exceed 1,600 watts, urging those in the market for a powerful vacuum to "act quickly" before they are sold out.
Current models boast an average of 1,800 watts.
Tesco said sales had risen by 44% over the past two weeks, with customers snapping up the most popular 2,000 watt models, and the Co-operative Electrical shop reported a rise of 38%.
Online electricals retailer ao.com said it had seen a 40% increase in sales week on week, with the surge predominately driven by "panic buying" of cylinder cleaners across all of its major brands including Dyson, Miele, Bosch and Hoover.
Ao.com head of small domestic appliances, Leanne Beswick, said: "We have seen a significant surge in sales of corded vacuums over 1,600 watts over the weekend.
"However, consumers need not panic buy. Even though these particular models will eventually be off the market, this doesn't mean that new and other existing models are any less effective - they are not.
"Although they may need to lose power to conform to the new regulations, they won't lose performance."
She added: "Consumers should also be aware that the only clause in the legislation regarding the removal of these models from the market is that manufacturers can no longer bring these vacuums into the UK. If there are models already sat in manufacturers' warehouses, and they can prove this, they are well within their rights to continue selling them to retailers.
"This means that as long as there is stock in the supply chain, we can continue to sell out old high wattage cleaners without a time period limitation. So there's no need to rush."
Dyson, which has never made a vacuum cleaner with a motor above 1,400 watts, said it had seen a 78% increase in sales following publicity about the new labels.
The company said its own increase in sales suggested consumers were actually after efficient technology that would save them money.
Sir James Dyson said: "It's a myth that bigger is better. Dyson has never made a vacuum cleaner of more than 1,400 watts because it is intelligent engineering that leads to high cleaning performance, not energy-thirsty motors.
"The motor cap is a sensible part of the upcoming regulation from Europe, as it can drive investment in efficient technology."
For the first time, the labels will give vacuum cleaners A to G ratings for energy use, cleaning performance on carpets and hard floors, and dust emissions.
The label also requires a minimum level of performance for the vacuum to be sold in the EU.
But the scheme is self-regulating, meaning that manufacturers will create their own labels, and Which? said it was unclear if the results were being corroborated by an independent third party.
The European Commission believes the new regulations will mean better vacuum cleaners for consumers.