Hargrove's agent, Phil Williams, confirmed the deal, which was reported by espn.com earlier Thursday. Williams did not disclose terms of the contract.
Hargrove has 19 1/2 sacks in 102 career regular season games. He played for Seattle last season and had three sacks in 15 games.
Hargrove acknowledged his excitement about joining the Packers in a post on his Twitter account, saying, "Here I come Packer Nation."
That's a considerable area of need for the Packers, who spent much of last season searching for a reliable replacement for departed free agent Cullen Jenkins. Mike Neal, a second-round draft pick in 2010, has been plagued by injuries and now will miss the first four games of the 2012 regular season after violating the NFL's performance enhancing substance policy.
Hargrove has had some trouble with the NFL as well, including a yearlong suspension in 2008 under the league's substance abuse policy. Hargrove has acknowledged past drug and alcohol use, and talked about turning his life around and hoping to become an example for others.
Hargrove also was subject to scrutiny after he was connected to the controversy surrounding the New Orleans Saints and the league's investigation into bounties, extra payments to players for big hits on specific opponents.
Sports Illustrated recently reported that during the Saints' NFC championship game win over the Minnesota Vikings in January 2010, Hargrove was overheard saying "Favre is out of the game! Favre is done! Favre is done!" after then-Vikings quarterback Brett Favre injured his ankle. Hargrove also was penalized for roughing the passer in that game.
Hargrove issued a statement calling his comments and the hit on Favre a mistake, and said he received "nothing" for it - presumably a reference to the bounty issue. It is not clear if Hargrove faces any discipline from the league.