German Chancellor Angela Merkel is ranked the most powerful in the world for the second year in a row in the annual list dominated by politicians, businesswomen and media figures.
US Secretary of State Hillary Clinton is placed second, followed by Brazilian President Dilma Rousseff, making the top three spots unchanged from that of last year.
Besides Sonia Gandhi, the list released Wednesday features three other Indians.
Padmasree Warrior, chief technology and strategy officer, Cisco Systems, and Chanda Kochhar, managing director and CEO, ICICI Bank, are ranked 58th and 59th, while Kiran Mazumdar-Shaw, founder and chair, Biocon Ltd, is placed 80th.
PepsiCo's Indian-American chairperson and CEO Indra Nooyi is ranked 12th.
The list named women involved in policymaking, entertainment, technology and nonprofit organisations, among other fields. They were ranked according to influence, the amount of money they control or earn, and media presence.
"These power women exert influence in very different ways and to very different ends, and all with very different impacts on the global community," said Moira Forbes, president and publisher of ForbesWoman.
Also in the top five were Melinda Gates, co-chair of the Bill and Melinda Gates Foundation and wife of Microsoft Corp co-founder Bill Gates, and Jill Abramson, executive editor of the New York Times.
US first lady Michelle Obama, who had topped the list in 2010, was ranked No.7.
The average age of the 100 powerful women from 28 countries was 55. They had a combined 90 million Twitter followers, Forbes said.