The singer-and-actress - who recently quit her job as a judge on 'American Idol' - made her debut at number 38 in the magazine's annual list while Shakira and Sofia Vergara also made the top 100, coming 40th and 75th respectively.
However, all three were beaten by Lady Gaga, who was in 14th position and Beyonce Knowles, who made it in at 32.
German Chancellor Angela Merkel topped the list with US Secretary of State Hillary Clinton just behind her in second place.
Brazilian President Dilma Rousseff was in third place again, while US First Lady Michelle Obama came seventh.
Moira Forbes, the head person at ForbesWoman, said of the list: "This year's Power Women exert influence in very different ways, and to very different ends, and all with very different impacts on the global community."
Oprah Winfrey, Ellen DeGeneres, Angelina Jolie, J.K. Rowling and Gisele Bundchen also all made the list with talk show host Oprah coming in highest at number 11.