The British actress will appear in season two of the hit Showtime drama, Deadline reports.
Robinson will play Roya Hammad, a Middle Eastern journalist with links to terrorist Abu Nazir (Navid Negahban).
The character will also become involved with Brody (Damian Lewis), delivering an ultimatum to the conflicted former marine.
34-year-old Robinson played Ilana Verdansky on Lost between 2009 and 2010. She has also appeared in Rome and X-Files spinoff The Lone Gunmen.
Damian Lewis recently admitted that his performance as Brody has elicited a mixed response from viewers.
"I don't mind playing unlikeable roles," said the actor. "I've done it before. One of the things you should seek to achieve as an actor is that your character is understood somehow."
Homeland will return to Showtime in the US on September 30. Channel 4 has picked up the rights to air season two in the UK, with a late 2012 broadcast planned.
Watch Damian Lewis discuss Homeland season two with Digital Spy below: