New York: Pop star Lady Gaga has been tagged the most powerful entertainer in the world by Forbes. Topping the annual list of the magazine, Gaga, who earned more than 91 million dollars over the past year has surpassed TV mogul Oprah Winfrey.

The magazine awarded her the accolade in part due to her large online following.

The 25-year-old singer, who was struggling to break into the music business and was virtual unknown three years back, has knocked Winfrey into second place for the first time in four years.

The 'Poker Face' hitmaker who came fourth in last year's list, has more than 32 million fans on Facebook and 10 million followers on Twitter – who she calls her 'Little Monsters'.

Most of Gaga's earnings in the past year came from a world tour which made her 75 million dollars.

Teen sensation Justin Bieber made his debut on the list at number three. The 17-year-old Canadian-born singer earned USD 53 million from his concerts and a 3D documentary.

Like Lady Gaga, he has a huge online following, with more than nine million Twitter followers, while his first song 'Baby' has been viewed 500 million times on YouTube.