Beckum tore his ACL during the Giants' Super Bowl victory over the New England Patriots in February and started camp on PUP.
He was eligible to come off the PUP list before the Washington game two weeks ago when the Giants activated defensive tackle Chris Canty off the PUP list.
Beckum gives the Giants another option in the passing game. He had five receptions for 93 yards last season, including a 67-yard touchdown against Green Bay.
He had seven catches for 45 yards during the Giants' postseason run last season.
Beckum has been practicing after spending the first six weeks on the PUP list.
Petrus is in his fourth year and will be subject to waiver claims until 4 p.m. Monday. A source said the team believes Petrus likely will be claimed on waivers.
Information from ESPN Senior NFL Anaylst Chris Mortensen was used in this report.