"Chinese buyers' global presence is fueled in part by a strong yuan and slowing domestic economy, both of which are encouraging Chinese investors to look further afield in an attempt to diversify their investments," the report said.
(Read more: Asia's commercial property deals set for record year)
London was also a winner with no. 3 ranked Russian buyers, who were targeting New York and Monaco as well, but they were bigger spenders, laying out an average $3.0 million a pop, it said.
Latin American buyers didn't make the top-10 list, but Knight Frank expects them to become more important for the new-build segment in the future, with Brazilian, Mexican and Venezuelan investors, already prominent in their region, increasingly looking further afield, targeting Miami, Paris and Madrid.
(Read more: Singaporeans snap up London homes as local market slows)
Private investors have turned to real estate as a "safe haven" for wealth preservation in the wake of the global financial crisis and the Arab Spring, with prime property prices in key locations, such as Dubai and Hong Kong, rising as much as 80 percent since early 2009, the report said.
"Buyers are increasingly drawn to cities they perceive to be sheltered from wider economic issues," with locations including New York, Monaco and Dubai meeting this requirement, it said.
Monaco and New York prices have risen around 8-14 percent over the 12 months ended in June, it noted.
(Read more: Miami mansion market sizzles, with no end in sight)
Political and economic risk at home were cited a key driver of international demand by 39 percent of survey respondents, it notes.
"The euro crisis, for example, has encouraged more buyers resident in the eurozone to look further afield in order to diversify their investments and move at least a portion of their wealth out of euros," the report said.
Influencing buyer behavior, recent sector cooling measures in Asia, many aimed at discouraging foreign buyers, have spurred many of the region's investors to look in other markets, while many southern European economies are actively wooing foreign buyers, it noted.
— By CNBC's Leslie Shaffer. Follow her on Twitter: @LeslieShaffer1