There were 145 female billionaires in the world at the end of 2014, compared with 22 in 1995, according to the study, conducted jointly by UBS bank and the PwC auditing firm.
Male billionaires were still much more plentiful at 1,202, but their number was multiplied by just 5.2 over the period, against 6.6 for women.
In Asia, the number of women billionaires rose more then eight-fold, from 3 to 25.
The study said at least half of Asia’s richest women are first-generation corporate chiefs, who got their education in Europe or the United States before making their pile back home.
In contrast, most of women billionaires in Europe and the US inherited their fortunes. The study pointed out, however, that they were often more active in developing their businesses than heiresses of previous generations.