Victoria Beckham lost out to rival denim design brand G-Star RAW at the WGSN Global Fashion Awards 2013 in London.
The 39-year-old, who won at last year's awards, had been nominated in the team-designers category for her jeans brand Victoria Beckham denim.
But she was overlooked for the award in favour of G Star RAW, a Dutch designer clothing company which specialises in untreated denim.
Shoe-designer Christian Louboutin also lost out in the Best Footwear and Accessories category, which was won by rival Nicholas Kirkwood.
Other winners at the event, which was hosted at the Victoria & Albert Museum this evening, included sportswear designers Sweaty Betty and the popular high street brand Gap Kids.
Meanwhile, Oliver Spencer won the coveted Best Menswear Designer award, and British-Turkish designer Erdem Moralioğlu won the prize for Best Womenswear.
Recent graduate Emma Shipley won the award for best emerging designer while Christopher Bailey, chief creative officer of London fashion house Burberry, was inducted into the WGSN Hall of Fame.