The likes of Justin Bieber, Taylor Swift and Lady Gaga also made an appearance on the list, which was complied by the mag across 15 categories after working with "a panel of expert judges" to decide on the final placings.
Adele made the cut following the success of her record-breaking album 21 - which has now sold over 23 million copies worldwide.
1D were honoured for the huge success of debut single What Makes You Beautiful, while RiRi's endorsement deals and sold-out shows were taken in to account.
Forbes stated: "In sum they represent the entrepreneurial, creative and intellectual best of their generation. Individually, they are engaging, surprising and incredibly hardworking."
Forbes' 30 Under 30 music stars list:
Tom Lehman, Ilan Zechory
Elias Roman, Peter Asbill, Elliott Breece, Eric Davich
James 'J' Sider
Sam Tarantino, Josh Greenberg
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