In an Instagram post, Matthews wrote that he was fed up by feeling he was disposable as an NFL player and that although he will always be a football fan, he will not miss the "fakeness" or "brainwashing" that he endured in the league.
In a statement titled "No Longer Exist," Matthews wrote:
"The game has given me and family so much but that No Longer Exist ... Beating your body up over and over for groups of people to give out a small % of the earnings that they don't even need for me No Longer Exist ... The endless training & hours away from my family No Longer Exist ...
"The brainwashing & dividing of culture for a small piece of jewelry No Longer Exist ... Being around too much Ego to even understand that someone has the same skin as you No Longer Exist ... People using me for Entertainment and not understanding that i Am a Black Man in America No Longer Exist
"As a receiver, people controlling your success No Longer Exist ... Being around just pure fakeness No Longer Exist ... The crowds cheering No Longer Exist ... The Touchdowns, Big Catches Fun Times No Longer Exist ... All the people that never talk to you then hit you up for tickets when they see you're close to them thinking you get them for free & act crazy when you can't get them for them No Longer Exist (lol)
"I am thankful to have become financially free but that income No Longer Exist (lol) ... It was cool being a Professional Football Player and getting to play a kids game for work I will always be a fan of the best sport in the world but for me that Kids game No Longer Exist"
On Saturday, Saints coach Sean Payton confirmed that it was Matthews' decision to leave the team, adding, "It's not for everyone."
Matthews, 29, joined the Saints in June after a minicamp tryout. But he was playing with the backup units throughout training camp. He caught one pass for 7 yards while playing 20 snaps in Friday night's preseason opener against the Minnesota Vikings.
Matthews was the Tennessee Titans' top wide receiver in the 2016 and 2017 seasons, but he asked for his release last year because of a diminished role and wound up catching just five passes for 24 yards in a total of eight games with the Titans and New York Jets.
Matthews also requested a trade before his final season with the Miami Dolphins in 2015 while skipping voluntary workouts, but he stayed with the team for one more season.
The 6-foot, 217-pounder has 230 career catches for 3,160 yards and 21 touchdowns in seven years.
ESPN's Mike Triplett contributed to this report.