Who was the last super bowl winner who lost their first game of the season?

The last Wild Card team to make the Super Bowl and lose was the 2008 Arizona Cardinals. The Cardinals were the 4th seed in the NFC playoffs.

They advanced to the Super Bowl by defeating the Atlanta Falcons in the Wild Card round, the Carolina Panthers in the Divisional Round and the Philadelphia Eagles in the Conference Championship game. The Cardinals lost to the Pittsburgh Steelers 27-23 in Super Bowl XLIII.