The Brazilian-born entrepreneur will avoid paying around $600m (£373m) in tax when he collects his share of the social network's stock value by becoming a resident of Singapore.
Saverin, who has lived in the Asian country since 2009, filed to renounce his citizenship in September 2011, but the move only came to light last week through a document published by the IRS.
"Eduardo recently found it more practical to become a resident of Singapore since he plans to live there for an indefinite period of time," a spokesperson said.
Saverin was Facebook's first chief financial officer, providing the funding Mark Zuckerberg required to get the operation off the ground. He left the company following a high-profile dispute with its current CEO.
The legal battle was depicted in the 2010 film The Social Network with Andrew Garfield playing Saverin, and Jesse Eisenberg as Zuckerberg.
Saverin holds a 4% share of Facebook's stock, placing his estimated personal wealth at $4bn (£2.5bn).