Victoria, who was escorted to the event Monday by husband David Beckham just two days after he was involved in a car crash, was presented with the Best Brand prize during a ceremony at Coliseum venue.
"Wow, thank you. I am so, so proud to be British and incredibly proud to have built my brand in the UK. I want to thank my team. I love you all so much and this is for all of you," she said.
"Harry Potter" star Watson was presented with the British Style Award by One Direction singer Harry Styles, who claimed the prize last year.
Poppy Delevingne joined fellow models Karlie Kloss and Joan Smalls in handing little sister Cara Delevingne the Model of the Year prize, and US Vogue editor Anna Wintour was feted for her years of contributions to the fashion industry with the Outstanding Achievement award.
Among the other attendees at the star-studded event were Rihanna, Rita Ora, Anna Kendrick, Lily Allen, Suki Waterhouse, Kylie Minogue, and Nicole Scherzinger.