The invites weren't given out until after the ceremony.
Created by invitationers Lehr & Black, Fergie and Duhamel's invitations were "a reflection of both of their personalities," says the Los Angeles business's Ellen Black.
"Fergie loves bling and has a love for unicorns and Josh loves nature," she says. "The artwork had leaves and hidden details like a unicorn and the invites were decorated with crystals."
"There's a current trend for celebrities to give out the invitation as a gift at the end of the wedding," says Black, who has also created invites for Jennifer Lopez, Eva Longoria Parker and Gwen Stefani. "That way, they can avoid the invitation being revealed before the wedding and can keep all the details a secret."
Accompanying the wedding invitation was a caricature of Fergie and Duhamel fishing. "Josh has a love for art," says Black, "and viewed it as giving away of piece of art."