Watson will take over advertising duties when Knightley's contract expires this summer.
A source told British newspaper The Mail on Sunday, "Emma has been slowly integrated into the Chanel brand. They have been dressing her for film premieres and parties over recent months to see if she is the right fit. Once it became clear she is growing into a beautiful young woman and wears the Chanel brand so elegantly, they had to sign her up."
Hermione's new gig will net her about $6 million. Not a bad payday for a fresh-faced 18 year old!