The team announced Friday that he also tore a ligament during Thursday's offseason training activity workout.
Beason went down defending a pass play. He walked off the field, but was later carted off for evaluation. He had X-rays, an MRI and a CT scan to determine the extent of the injury.
His status for the season opener Sept. 8 against Detroit remains in question. Beason said in a statement released by the team that he hopes to be back for the opener.
''It's not season-ending, so I'm happy about that,'' said Beason, who had at least eight tackles in eight games last season after arriving in a trade with the Carolina Panthers.
He'll be evaluated by a specialist in Charlotte on Monday before starting a rehabilitation program.
He's had his share of injuries during his career, including a ruptured Achilles tendon and microfracture reconstructive knee surgery. The Giants signed him to a three-year, $16.8 million contract in the offseason. He made 93 tackles and had 12 interceptions in 12 games for the Giants.
''It's just one of those things. You have freak injuries,'' Beason said in the statement. ''I was just changing directions. I would say that the movement was a little unorthodox, I was flexing with the big toe in the ground and then I pivoted on it all the way around.
''It's a movement that I often do that allows me to come in and out of my breaks faster. I literally felt like I stepped in like a sprinkler head hole. I just felt it give right away, so the next step I knew I couldn't put the foot down.''
After Beason went down Thursday, Giants coach Tom Coughlin expressed how vital he's been to his defense.
''He's very important, because of the nature of the man, the player, his attitude, his leadership skills, what he brings to the table, he's very important,'' Coughlin said.
In the meantime, the Giants will use fourth-year veteran Mark Herzlich, free-agent signee Jameel McClain and fifth-round draft pick Devon Kennard out of USC as replacements for Beason.