The reality star will portray a new character called Nikki, a love interest for Fred (Ben Feldman) who goes on to become business partners with his ex Stacy (April Bowlby).
Kardashian will make her first appearance in the Lifetime show's season four premiere and have a multi-episode story arc.
She expressed her excitement about the role in a brief blog post, writing: "I can't wait to get to work with everyone on set!"
Drop Dead Diva creator Josh Berman said: "I'm ecstatic to welcome Kim to the Diva family. In discussing the role of Nikki with her, I'm blown away by her smarts, sense of humour, and passion.
"This series is all about reinvention, and I'm so excited to see Kim 'reinvented' in the world of Drop Dead Diva."
Guest stars in the last season of Drop Dead Diva included Paula Abdul, Lance Bass, LeAnn Rimes and Mario Lopez.
The show is slated to return later in 2012, having been picked up for a fourth season last September.
> 'Drop Dead Diva' Margaret Cho 'would come back as Kardashian'