The 37-year-old former Spice Girl, who gave birth to baby girl Harper Seven in July, has reportedly generated sales of over £15m for her clothing range, which is favoured by celebrities such as Cheryl Cole and Eva Longoria.
A source told UK newspaper, the Daily Mail: 'Victoria never dreamed her clothing range would be successful. She is close to eclipsing her husband David!'
The source added that the mum-of-four's fashion business is currently due to exceed all expectations with its figures up 71 per cent on last season for the first quarter of 2011.
Posh, whose clothes can sell for up to £5,000, recently launched a more affordable second fashion range – Victoria by Victoria Beckham – which she claims channels her “inner girl”.