The law will come into force on 6 April 2020 and will give industrially manufactured items such as furniture, lighting and jewellery the same copyright protection as works of art, books and music.
Registered designs in the UK are only protected for 25 years, but the new law will give them protection until 70 years after the death of the designer.
"Great design forms an integral part of our lives whether it be architecture, jewellery or home furnishings," wrote UK intellectual property minister Lucy Neville-Rolfe in a document announcing the decision. "Both cutting-edge designs and those that have stood the test of time continue to be in high demand and we need to ensure designers have an appropriate incentive to create."
"But currently these artistic designs lose copyright protection after 25 years if they have been mass produced," she added. "This is unfair in comparison to other artistic works, like literature and music, which are protected for the life of the creator and 70 years."
The changes to the law are contained in the Enterprise and Regulatory Reform Act 2013, which was passed on 25 April 2013 and brought IP protection in the UK into line with most other European countries.
However the government delayed implementing the law while it consulted with businesses that would be affected by it. Design brands including Vitra, Artek and Flos urged the government to implement the law as soon as possible while replica furniture retailers argued for a delay.
"Having listened carefully to the views of designers and businesses, the Government has made the decision to implement the change in law in April 2020," said Neville-Rolfe. "When this happens, we hope the change will bring rewards for British designers and encourage a new generation to innovate and grow."
The change to the law followed a wide debate on copyright for furniture designs, after the British prime minister's wife purchased a reproduction of the Castiglioni brothers' iconic Arco floor lamp in 2011.
This led to a campaign headed by Elle Decoration editor Michelle Ogundehin, who rallied licensed manufacturers and retailers including Vitra, Fritz Hansen, Skandium and Aram to challenge the intellectual property rights laws in the UK.
Writing in Dezeen recently, Vitra chairman Tony Ash argued that copyists are "eating away at the very creativity of our industry". Chris Diemer of replica furniture retailer Voga responded by saying that firms like his are making good design affordable for the masses.
Main image is a replica Arne Jacobsen Egg Chair from replica retailer Voga.