Penthouse D at One Hyde Park was sold to an eastern-European buyer.
Christain Candy's CPC group confirmed that it had sold the penthouse apartment but did not reveal the sale price or buyer.
A spokeswoman said: "CPC Group is not able to comment on the sale price or the purchaser. However, global professional valuation companies have valued the finished penthouse at circa £160 million-£175 million."
The development consists of 80 flats in four pavilions in a prime location in the UK capital with views across the city and Hyde Park.
The penthouse was designed by architect Richard Rogers, with management and interior design by Candy & Candy.
Nick and Christian Candy bought the Knightsbridge site of the former 1950s office block Bowater House in 2004 for £150 million.