In a post on the social network, Mark Zuckerberg said he hoped the move would connect "millions" to the internet.
The satellite, due to launch next year, is currently being built under a partnership with French firm Eutelsat.
It would allow mobile users to download an app containing free data access to selected services, including Facebook.
The decision underlines the scale of the billionaire's ambition to boost connectivity in emerging internet markets but the scheme has been met with opposition in many countries such as Uganda, India and Indonesia.
Critics argue that it risks damaging investment by competing mobile operators and the principle of net neutrality because only selected services will be available by Internet.org.