The 43-year-old designer appeared on Thursday's episode of CBS' The Late Late Show With James Corden and confirmed that Prince Harry's bride to be would not be wearing one of her dresses on her wedding day.
"Sadly not, but I'm sure she will look incredible in whatever she wears," Beckham said.
The mother of four and her husband, David Beckham, attended Prince William and Kate Middleton's wedding in 2011 and are assumed to be attending Prince Harry's nuptials.
However, when asked if they will be at the royal wedding, Beckham played coy. "I don't know," she said, stumbling over her words.
"She's totally going," Corden exclaimed as Beckham burst into laughter.
"Yes. England is so excited. It is so great, isn't it?" she responded. "I mean, it's so great. They look so happy."
There is also speculation that the Spice Girls will be reuniting and even performing as part of the royal wedding festivities. While Beckham did not confirm these reports, she did agree to do a "Carpool Karaoke" segment with Corden and her former girl group.
In an exclusive interview with ET last month, Mel B also confirmed that she and the Spice Girls would "be doing stuff this year together."