The Czech born bombshell is the brand's first celebrity spokesperson since Lauren Bacall mugged for the store 26 years ago.
Nemcova will also design a line of jewelry for the chain, entitled Petra for Fortunoff Collection. The gems will retail from $125 to $5000, with a portion of the proceeds going towards Petra's Happy Hearts Fund, which provides aid to children who have suffered loss as a result of a natural, economic or health related disaster.
In 2004, Petra survived the devastating tsunami while on vacation in Thailand.
Regarding the jewelry, Petra says she hopes it is able to "add a bit of light and hope to your outlook each and every day."