The Court of Arbitration for Sport overruled the not-guilty verdict handed down by the AFL Anti-Doping Tribunal upon appeal from WADA.
The 12 players who remain at Essendon and five players who have moved to other clubs will miss the 2016 season.
“Regrettably we can confirm the Court of Arbitration for Sport has found 34 past and present players guilty of committing an anti-doping rule violation,” a club statement read.
“As a result, the players - including 12 currently listed with Essendon - have been suspended for the 2016 season. The club is currently digesting the decision and we will provide a further update later today.”
This ban will also impact former players who holding coaching positions or playing at local level.
Jobe Watson and Dustin Fletcher (now retired) may be given slightly longer suspensions given their involvement in the 2014 International Rules series.
The three-member panel did not grant the players a discount for no significant fault or negligence that would allow a discount on a guilty verdict.
The players have the ability to appeal the decision via a higher court in Switzerland.
It was revealed Essendon had self reported to the AFL and ASADA on February 7, 2013, a day described as “blackest day in Australian sport”.
This result is likely to be the final chapter in an investigation spanning almost three years.