The league and players' union found that Brown was among three players who misrepresented their vaccination statuses. A former personal chef of Brown's said earlier this month that the wide receiver had obtained a fake COVID-19 vaccination card over the summer.
Also suspended for three games were Buccaneers backup safety Mike Edwards and free-agent wide receiver John Franklin III, whom Tampa Bay waived in August. All three players accepted their discipline and will not appeal, according to the NFL.
Brown's and Edwards' suspensions are without pay. Both will be eligible to return to the Buccaneers' lineup for the team's Dec. 26 game against the Carolina Panthers. The NFL and NFLPA negotiated the length of the suspension ahead of Thursday's announcement, sources told ESPN's Dan Graziano.
All three players are now vaccinated and admitted wrongdoing to the league in the investigative process, a source told ESPN's Jeremy Fowler.
"The NFL-NFLPA jointly reinforce their commitment and further emphasize the importance of strict adherence to the protocols to protect the well-being of everyone associated with the NFL," the league and players' union said in a statement.
The league's investigation found that Brown brought a fake vaccination card with him to training camp, but shortly after he arrived someone told him having one could get him in trouble, so he made the decision to get vaccinated, sources told Graziano.
Brown's attorney, Sean Burstyn, said in a statement that Brown "continues to support the vaccine for any person for whom it is appropriate."
"The NFL made its determination and, instead of going through the drawn out and distracting process of challenging the outcome, Mr. Brown wrapped this up promptly and he will make the most of this time by treating his ankle injury," Burstyn said. "Mr. Brown will be motivated, well rested, and in the best shape of his life when he returns in week 16."
Brown was not expected to play in the next two games because of an ankle and heel injury that has kept him out since Week 7, a source told ESPN's Adam Schefter on Wednesday.
The Bucs on Friday signed wide receiver Breshad Perriman to their active roster, agent Drew Rosenhaus told ESPN's Adam Schefter.
Chef Steven Ruiz said earlier this month that Brown had his girlfriend, model Cydney Moreau, reach out to him over the summer to obtain a fake vaccination card. After Ruiz was unable to acquire a fake card for Brown, he said that a few weeks later the wide receiver showed him ones he had for himself and Moreau that Brown said he had purchased.
Ruiz told ESPN that Brown had obtained his fake vaccine card from a Buccaneers teammate. Ruiz declined to name the other player.
Burstyn had denied that Brown obtained a fake vaccine card.
Brown said Wednesday when asked about his vaccine card on the Richard Sherman Podcast, "That's the sad part. The country say, 'You're innocent until proven guilty,' but you're guilty till you show innocence, because anything someone says, everyone's already magnifying it, and if you come out and say anything, you just put yourself in deeper holes because now it's like ... I learned to realize criticism is answered with achievement. When people criticize you, there's no need to respond or worry. ..."
A day after Ruiz's initial allegation, Buccaneers coach Bruce Arians said the team did its "due diligence" in vetting players' vaccine cards, adding, "I really don't think it's a story."
"We appreciate the League's timely handling of this matter and recognize the importance of the health and safety protocols that have been established. We will continue to implement all league COVID-19 protocols," the Buccaneers said in a statement Thursday.
Some 80% of the NFL's vaccinated players were vaccinated at team facilities, sources told Graziano, meaning there is no question about the authenticity of their vaccination cards. The NFL also found that there has been no difference between the positivity rate among players who were vaccinated at team facilities and those who were vaccinated elsewhere, sources said, which is a reason the league does not fear a rampant fake vaccination card issue.
During the 2020 season, the Buccaneers' mantra was "beat the virus." In September, Arians reported that all players and staff members had received the COVID-19 vaccine, becoming the second NFL team to do so.
While Brown did not publicly discuss his vaccination status, Edwards wore a mask when he met with reporters at the beginning of training camp, which is required for players who are unvaccinated. Asked about his vaccination status, Edwards said at the time, "I don't really want to talk about vaccinations really. It is what it is. I don't really want to get into that."
Asked whether he would change his mind, Edwards said, "I don't know. We'll see." After that, Edwards did not wear a mask when speaking with reporters.
Edwards, who has lined up at safety and nickelback, forced a fumble in last week's win over the Indianapolis Colts and leads the team with three interceptions. He was named NFC Defensive Player of the Week in Week 2 after recording two pick-sixes against the Atlanta Falcons.
ESPN's Jenna Laine contributed to this report.