The star will play supervillian Digger Harkness/Captain Boomerang in a multi-episode role, according to Entertainment Weekly.
The character will be a highly-skilled ex-ARGUS operative who is hungry for revenge against his former employers.
Tarabay, who will appear from season three's seventh episode, follows fellow 'Spartacus' stars Manu Bennett (Deathstroke) and Cynthia Addai-Robinson (Amanda Waller), who also joined 'Arrow'.
Australian actor Matthew Nable was recently cast in the comic book series as Ra's al Ghul.