Arabic and Hebrew will now be available from a drop-down menu at the bottom of the homepage.
"It's the first time Arabic speakers will be able to use Facebook in their own language," said Ghassan Haddad, the Facebook director of localisation. "It's potentially huge," Haddad added.
Facebook said 850 Arabic speakers and 870 Hebrew speakers had helped with the project.
The site's developers built a mechanism to detect the gender of the user and select the translation that matches it and used Modern Standard Arabic, which is used in the media and other formal and religious circles.