Bryant will not appeal the suspension, which begins immediately. His agent had said on Saturday that Bryant had planned to appeal.
He was scheduled to make $600,000 this season.
Bryant was suspended for the first four games of the 2015 regular season due to violations of the same policy.
The former fourth-round draft pick out of Clemson is reportedly fighting depression and will enter rehab.
The Washington Post reported that Bryant missed several drug tests, which counts the same as failed tests and had a diluted specimen that is also the same as a failed test along with a failed test for marijuana.
One of his agents, Brian Fettner, confirmed the ban stems from multiple missed drug tests.
"We clearly miscalculated the issue. His isn't a party issue. It's a coping issue and a depression issue, and he's got to take care of it.
"This is the biggest cry for help I've ever seen. And that hurts," Fettner added.
Bryant will be eligible to apply for reinstatement by the league no sooner than 60 days before anniversary of his suspension.
Bryant caught 50 passes for 765 yards and six touchdowns in 11 games last season.
Bryant has 76 catches for 1,314 yards and 14 touchdowns in 21 regular-season NFL games, and 19 catches for 244 yards and two TDs in three playoff games.
Pittsburgh's decision to sign receiver Darrius Heyward-Bey to a three-year extension was a direct result of Bryant's potential absence in 2016, a source told ESPN.
(Editing by Frank Pingue)