Her rendition of Hallelujah became the fastest-selling single by a solo female artist in the UK - shifting more than 500,000 copies in a week.
Given her deep, soulful voice and diva looks, her victory may not seem surprising. But look at her weekly scores across the 10-week competition: she barely won a round in the run-up to the final, and often ranked well down the scoreboard. Meanwhile, the angelic Eoghan Quigg won over half the rounds - only to fall at the final hurdle.
The business world has its winners and losers too. With the economy proving a particularly tough judge, increasing numbers of firms are falling by the wayside. If the outcome of The X Factor was hard to second-guess, trying to predict which businesses will make it through successive rounds of the recession may be just as difficult.
But the TV phenomenon provides clues. Alexandra triumphed because, in the weeks running up to the final, she won the support of the fans of the other ousted contestants. Eoghan's following, though, stayed stable. In business, WH Smith will probably benefit from the demise of Woolworths. Indeed, success in business is not simply about individual performance: your rivals' under-performance may be just as significant for your fate.
If you don't want to cede the crown to the Alexandras of your trade, consider carefully how to attract custom from those who have fallen. To steal a famous phrase from the show: you want the judges telling you that 'you made the sector your own'.
- Jennifer Harris is director of JRBH Strategy & Management, www.jrbh.co.uk