Williams was hospitalized after being injured in a construction accident last week in Hillsborough County.
"We are saddened to hear of the untimely death of Mike Williams, which has left our organization, his former teammates and fans with heavy hearts," the Buccaneers said in a statement. "We send our deepest sympathies to his family and loved ones as they mourn this tragedy."
Williams was born in Buffalo, N.Y., and attended Syracuse. His 20 career receiving scores are tied with Pro Football Hall of Famer Marvin Harrison for the second-most in school history, trailing only former NFL All-Pro Rob Moore.
Williams was a fourth-round pick by the Buccaneers in the 2010 NFL Draft. He totaled 964 yards and a career-high 11 touchdowns on 65 catches in 16 starts during his rookie campaign.
He totaled 3,089 yards and 26 scores in 63 career appearances. Williams spent his first four seasons with the Buccaneers. The Buccaneers traded Williams to the Bills in 2014.
Williams signed with the Chiefs during the 2016 off-season, but failed to make their regular-season roster.
"We are saddened to learn that former Bills Wide Receiver Mike Williams has passed away," the Bills said. "Our deepest condolences are with his friends and family."