Little Mix's earnings reportedly increased by almost five times in a year.
The chart-topping girl group - which features Jesy Nelson, Leigh-Anne Pinnock, Jade Thirlwall and Perrie Edwards - shared as much as £6.6 million in dividends from their live music company, which they jointly own.
As a result, the girls each pocketed £1.65 million from the venture, which is listed under the name Eternal Magic Touring.
The pop stars created the company in 2015 and their most-recent set of accounts - which cover the year to August 31, 2018 - was their most profitable to date.
For the last financial year, the company recorded a £2.8 million profit and held £5 million in funds, according to the Sunday Mirror newspaper.
Meanwhile, Perrie previously hit out at the entertainment business, saying it is fake.
The blonde beauty revealed that working in the industry has changed her perception of it.
She explained: ''We've seen how the real industry works and none of it is real.''
Perrie's sentiment was echoed by Jesy, who argued the Kardashians have been particularly guilty of creating false beauty standards.
Jesy - who has more than five million followers on Instagram - reflected: ''It's gone too far with the Kardashians, hasn't it?
''They all look so perfect and you never see a bad picture of them, but we're in the industry and we know how much they can change a picture.
''When the Kardashians wake up, they look normal. If I was a teenager today with all these images of perfection on Instagram, I would literally have the lowest self-esteem.''