According to cast member Amber Atherton, Alex Watson will appear in the third series of the E4 reality show in 2012.
Made in Chelsea producers apparently believe that he will rival alpha male lothario Spencer Matthews.
Atherton told Closer: "The producers think it would be amazing to get Alex on the show. He's good-looking so he'd make great competition for Spencer."
Alex, 18, has previously appeared as an extra in the Harry Potter movies, in which his elder sister stars as Hermione Granger.
Emma recently had a relationship with Chelsea star Francis Boulle, who ended their romance due to the extent of her fame.
> Emma Watson brother psyched by ad shoot