They praised her "finely tuned business acumen" for expanding her fashion empire into a business with a £30m turnover and a staff of 100.
Editor Matthew Gwyther accepted that some may "scoff" at the fact that the former Spice Girl came top.
But he said she had created "a company that is both real and wildly successful". Gwyther admitted "some will say she's never been taught how to cut a pattern, or iron a pleat on a fashion course... Doubters will claim she's just the wife of the world's most famously over-tattooed ex-footballer. It's all come to her far too easily."
But he pointed out that "celebrity has long been a powerful commercial tool" and called her "an adept exploiter of her own celeb value".
And he said doubters could not argue with the figures as she has achieved - a sales growth of 2,900% and employment growth of 3,233% over the past five years, adding "her numbers are impressive".
The former Spice Girl launched her fashion label in 2008 and by 2011, she won designer brand of the year at the British Fashion Awards.
In September, she opened her first shop in London's Mayfair.
Her company includes a lower-priced Victoria line and she also sells luxury handbags for prices up to £18,000 each.
The magazine estimated her wealth at £210m.