Tens of thousands of drawings and models produced by the 1960s group will be moved from storage in the UK to the Herzog & de Meuron-designed M+, set to open later this year in Hong Kong's West Kowloon Cultural District.
The £1.8 million sale was approved by the UK's government's Department for Digital, Culture, Media and Sport, despite an Arts Council committee recommendation to block it, reported the Architects Journal (AJ).
Museum experts had objected to the collection of important British architectural works being moved overseas, but no buyer planning to keep the collection in the UK could be found.
Archigram members to celebrate with "drink in Hong Kong"
Founded in the 1960s, Archigram became famous for its experimental approach to design, with futuristic projects such as Plug In City and Instant City. Members included Peter Cook, Warren Chalk, Ron Herron, Dennis Crompton, Michael Webb and David Greene.
The group's avant-garde work informed the work of architects including Richard Rogers, Renzo Piano and Norman Foster.
Peter Cook, one of the surviving members of Archigram, told the AJ that he welcomed the sale.
"We'll have a drink in Hong Kong I should think," he said. "When we were hawking it around, there were some places that would have put it into a basement only for scholars to see," he said.
"I hope that M+ will allow people to see it."
The collection had been valued at £2.8 million, but Cook, Crompton and the other surviving members said they were happy to sell at a lower price to ensure the works would be somewhere the public could enjoy them.
Cook said the dearth of UK buyers demonstrated a "certain blinkeredness" in the country's attitude to architecture. The architect has previously been critical of the British architectural scene, which he diagnosed as going through a "dull period".
Collection previously kept in "various cupboards"
Dennis Crompton, another original Archigram member, said he had previously been keeping the group's work under beds and in "various cupboards".
"Now it will be all together in a place which is young and enthusiastic," Crompton told the AJ, adding that he sees M+ as China's answer to MoMA or the Centre Pompidou.
M+ is set to become one of the world's most important art and design museums. The museum's curator-at-large Aric Chen previously told Dezeen M+ would put "Asia at the centre" of the narrative about design, rather than relegating it to the sidelines like Western curators tend to.
Images courtesy of the Archigram archive.