Barnett was among the first Packers to return to Lambeau when the doors to the team facilities re-opened to players Tuesday morning. He didn't stay long, then posted a series of messages on his Twitter account making it clear he had been told his time with the Packers is over.
"Just met with Ted," Barnett posted, presumably referring to Packers general manager Ted Thompson. "Thanks for the great 8 years."
Barnett said he was "very blessed" to be a part of "such a great tradition and great fans."
Barnett was told the Packers will try to trade him, but if they are unable to do so, he will be released, a source informed ESPN's Andrew Brandt.
Barnett, who finished last season on injured reserve after hurting his right wrist Oct. 3, said he was happy to be part of the team's run to the Super Bowl championship last season and "will always keep a special place in my heart for this team and city."
Barnett did not speak to reporters as he left Lambeau. He did stop on his way in earlier Tuesday morning, saying he was ready to play.
"We could start right now, man," Barnett said. "I'm ready to go. My wrist should be cleared. I saw 'Doc' about a couple months ago, he said it was fine. We'll see what happens. Physically, I'm ready to go. Mentally, I'm ready to go. Emotionally, I'm ready to go."
Before heading into Lambeau, Barnett shrugged off recent speculation that he would be traded or cut.
"To be honest, a lot of the talk hasn't come from anybody in here, it's come from (the media)," Barnett said. "So I'll wait for them to come talk to me, I'm sure my agent will talk to them, I'll let them handle that business. But for me, I just prepare, (get) ready to play and see what happens. I've got two years left on my contract, so I'm not really focused on the rumors."
Barnett has been a cornerstone of the defense since the Packers took him in the first round of the 2003 draft. He has started 107 regular-season and six playoff games in eight seasons.
But his relationship with the team was strained during last year's Super Bowl run. When Barnett found out that injured players wouldn't be a part of the Packers' team photo taken a few days before the Super Bowl, Barnett voiced complaints on his Twitter account. The team eventually relented and allowed injured players to participate in the photo, but the issue became a distraction as the team prepared for the game against the Steelers.
Barnett also has finished two of the past three seasons on injured reserve, including a season-ending right knee injury in 2008.
And given that the team signed Desmond Bishop to a contract extension late last season, and reworked A.J. Hawk's deal in March, Barnett's $5 million-plus salary may have been prohibitive for a player who would be expected to be a backup at inside linebacker.
Packers officials are not commenting on Barnett's status. Teams can trade players beginning Tuesday and cut players Thursday.
Several other Packers players were at Lambeau, including Donald Driver, wide receiver Brett Swain and tight end Tom Crabtree. The Packers open training camp Friday and have their first practice Saturday.
Information from ESPN business analyst Andrew Brandt and The Associated Press was used in this report.