The Steelers best seasons were when they won the Super Bowl .
The Steelers best season , as far as their record , was 2004 , they went 15 - 1 and lost the championship game .
The Steelers best seasons were when Steelers won the Super Bowl .
The Steelers best season , as far as their record , was 2004 , they went 15 - 1 and lost the championship game .