A readiness hearing was set for March 23 in San Diego County Superior Court.
Jackson's attorney entered the plea via fax.
Jackson, on probation from a 2006 DUI conviction, faces charges of driving under the influence of alcohol and/or drugs and driving with a blood alcohol level of 0.08 percent or higher.
Jackson was arrested on Jan. 6, five days before the Chargers were eliminated from the playoffs by the eventual Super Bowl champion Pittsburgh Steelers.
Chargers defensive tackle Jamal Williams was arrested on suspicion of DUI on Feb. 1.