Former erotic photographer Westwood, son of legendary British fashion designer Vivienne Westwood, wants "good looking" Assange, 42, to appear with six other models as part of a fringe event during London Fashion Week in September.
"Julian is a popular hero," the designer said in a statement given to AFP.
"He has done a great deal to change public opinion.
"Through WikiLeaks people have been able to compare the facts with the official version of the story.
"He is a good looking man and I hope he is going to model," he added.
Mother Vivienne is also a keen supporter of Assange, and wore a T-shirt carrying the slogan "I am Julian Assange" when she paid him a visit at the embassy in 2012.
Other celebrities to visit Assange include Lady Gaga and director Oliver Stone.
Hollywood A-lister George Clooney has been invited to the show, which is inspired by Clint Eastwood's costume in the spaghetti western films, according to Westwood's PR spokesman.
Assange first sought refuge at the embassy on June 19, 2012, to avoid extradition to Sweden, where he is under investigation on allegations of sexual assault.
