Her entry says: "New Zealand's biggest star has rocketed to mainstream acclaim with debut album Pure Heroine and unexpected hit Royals. She's already cashing in with a (US) $2.5 million publishing deal, and more is undoubtedly on the way.''
Seventeen-year-old Lorde rocketed to international fame last year with the release Royals and her first album, Pure Heroine.
Her inclusion in the Forbes list comes after she topped Time magazine's most influential teenagers in the world list in November.
Lorde made the No.1 spot out of 16 teenagers from around the world, followed by golfer Lydia Ko in second place.
Time magazine said the proof of Lorde's success came when New York City Mayor-elect Bill de Blasio won the election and walked on stage to Lorde's defiant Royals.
Signed by a label at age 13, Lorde surpassed Miley Cyrus in September for the top spot on iTunes with the hit song.
Time said Lorde was "forging her own path", turning down an opportunity to join Katy Perry on tour because it "didn't feel right" at the time.