The Super Bowl champions announced the deal on Tuesday, the second safety the Giants have signed in the offseason.
A third-year pro, Brown played eight games with the Indianapolis Colts last season. He was originally drafted by the Oakland Raiders in the seventh round in 2010. He spent two weeks on the practice squad before being signed to the active roster and playing in 15 games, recording 35 tackles.
The Raiders waived Brown at the end of training camp last season. He was briefly with the Carolina Panthers before joining the Colts on Sept. 21. His season ended in late November when he was placed on injured reserve with a quad injury.