The Panthers also officially signed cornerback Dante Wesley and released cornerback Curtis Deloatch and receiver Chris Horn.
The 28-year-old Manuel started all 16 games at strong safety for the Packers in 2006 after signing a five-year, $10 million free-agent deal before the season.
But Manuel, who was blamed for giving up several big plays last season, lost his starting job in the preseason. He was one of Green Bay's final cuts to get to the 53-player limit.
Manuel spent the previous two seasons with Seattle.
"Marquand is a guy we feel fits into what we're looking for," Panthers general manager Marty Hurney said. "He's played safety at a high level in this league."
Manuel will provide the Panthers with experience where they desperately needed help. Veteran safety Mike Minter announced his retirement in training camp and fellow projected starter Nate Salley missed most of the preseason with a knee injury.
"We feel very fortunate to get a player of his caliber," Hurney said.
Wesley will replace Deloatch as the fourth cornerback behind Ken Lucas, Chris Gamble and Richard Marshall.
"We didn't want to lose Dante when he left for Chicago," Hurney said. "He's an excellent special teams player and a good corner. We just thought as the fourth corner he was the ideal fit for us."
Copyright 2007 by The Associated Press