Washington County made the final score 28-14 in the closing minutes when Dane hit DeMarcus Holcombe for a 19-yard touchdown.
Freshman Allen Rios was 4 of 4 on extra points for Tanner, while Jon-Michael Davidson finished 2 of 2 for the Bulldogs.
Stephens rushed for 139 yards and had a 2A Super 6 record-breaking 29 carries.
Eight seniors — Greg Maclin, Bubba Smith, Kendrick Jamar, Fred Rich, Dexter Douglas, Kyle Shoulders, Tray Fletcher and Rashard Gill — led a youthful 34-member team with 17 ninth- and tenth-graders.
The Rattlers, who defeated 3A state champion Madison Academy 13-7 during the first week of the regular season, have compiled a 49-4 record in the past four seasons.
Tanner is the first county football program to win a state championship since Clements in 1966.
“The thing I will never forget is how my teammates and me came together,” Baker said. “We all came together as a family, and worked as one to accomplish our goal. We’re going to come back next year and try to win another championship.”