The five-strong band topped an under-30s rich list with a combined fortune estimated at £59.33million.
The heartthrobs beat Harry Potter star Daniel Radcliffe to the top spot, bumping him down to second place after he had held the crown since the list was established in 2010.
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"One Direction are young, talented, staggeringly good looking and adored by millions," said Lucie Cave, editor-in-chief of Heat magazine. "To that we can now add 'rolling in cash'. No one said life was fair."
The boys' – Harry Styles, Niall Horan, Zayn Malik, Louis Tomlinson and Liam Payne – combined earnings come from TV shows, movies, record sales and product endorsements.
They were crowned Britian's richest under-30's after their finances were examined by a panel of industry experts.
One Direction – who have just released the cover of their new album Midnight Memories – were included as a single entry because their earnings were generated by the boy band as opposed to the boys individually.
Robert Pattinson came in at number three with a personal fortune of £44.16million, followed by English rose Keira Knightley.
Another Harry Potter star featured high up in the list – with £27.93million, Emma Watson was in fifth place. Skyfall singer Adele closely followed with a fortune of £27.54million.
DJ and music producer Calvin Harris was this year's highest new entry, coming in at number 8 with £22.2million.
Cheryl Cole and Leona Lewis also made it into the top ten.