"This year she finds herself among eight candidates vying for an even higher post: UN Secretary-General."
The magazine acknowledges that the former New Zealand Prime Minister has been credited for bringing greater efficiency to her agency and is considered "a front-runner" for the Secretary-General role.
Other powerful women named on the list include US First Lady Michelle Obama, at number 13, Democratic presidential hopeful Hillary Clinton, at number 2, and talk-show queen Oprah Winfrey, who features at number 21, just before Ms Clark.