The former Spice Girl revealed that she took her son Romeo and the family to watch Bieber record his most recent album as a birthday gift, but added that the 18-year-old mistook Romeo for another celebrity child.
"For Romeo's birthday, as a surprise, the family took him to hang out in Justin Bieber's studio while he was recording his Christmas album," Beckham told Vogue.
"Bieber sweetly sent the boys signed guitars afterward, but Romeo's was signed to 'Pax'," she continued. Pax Jolie-Pitt is the son of Angelina Jolie and Brad Pitt.
Beckham recently confessed that she was thrilled to see Beyoncé wear one of her dresses to a fundraiser, describing the singer as "one hot mama".
The 37-year-old designer previously said that she is too much of a fashion fan to be seen wearing Ugg boots or tracksuits.