Hong Kong was the first financial center outside mainland China where trading of yuan was authorized. London banks have traded yuan since early last year.
"Now London is a major global offshore center for the trading of the Chinese currency," Osborne told reporters.
Britain and China signed an agreement in June to have their central banks swap 200 billion yuan for 20 billion pounds.
The European Central Bank and Beijing announced a similar agreement this month to swap 350 billion yuan for 45 billion euros. That suggested Frankfurt also might be in to become a center for business denominated in yuan.
Also Tuesday, Osborne said China's state-owned banks will be allowed to expand their operations in Britain by setting up wholesale branches.
Cameron was forced to abandon his April trip after China said he would not be able to meet senior officials. Some lower-level meetings also were put on hold.
British diplomats say Cameron's visit is being rescheduled but a date has yet to be announced.