The Packers announced the move Wednesday afternoon. Asked about Peprah's status earlier in the day, Packers coach Mike McCarthy said he was "waiting for more information" from Peprah's physical exam.
Packers players reported to camp Wednesday morning for physicals and meetings. Their first practice is Thursday morning.
The move leaves the Packers with even more questions at safety, where the team is looking for a replacement for Pro Bowl safety Nick Collins. The Packers released Collins in the offseason, concerned about his ability to safely return from a significant neck injury he sustained last season.
Peprah, who filled in last year after Collins was injured, was expected to compete with second-year player M.D. Jennings and rookie Jerron McMillian in training camp. Jennings played in 15 games last season and McMillian is a fourth-round pick out of Maine.
Veteran cornerback Charles Woodson is not expected to make a full-time move to safety, but could see his already versatile role in the defense change slightly.
Peprah appeared in 67 games with 26 starts during two separate stints in Green Bay (2006-08, 2010-11). He played briefly for Atlanta in 2009.
Peprah played a significant role in the Packers' Super Bowl championship season, taking over as the starter after an injury to Morgan Burnett.
Peprah has seven career interceptions, all in the past two seasons.
The Packers also signed guard Greg Van Roten and released guard Grant Cook.
Van Roten, a 6-foot-3, 303-pound rookie out of the University of Pennsylvania, twice earned first-team All-Ivy League recognition and started all 30 games over his final three seasons for the Quakers.
Cook, a rookie out of Arkansas, signed with Green Bay as an undrafted free agent on May 14.