Blair was selected by the Vikings in the 2nd round of the 1974 draft out of Iowa State. He played all 12 seasons of his career as a Viking (1974-85), playing in 160 career games with 130 starts. The Linebacker still holds the team record with 20 blocked kicks, 23.0 sacks, and 16 interceptions. He notched 230 tackles in 1981, the 3rd-most in a season by a Vikings player.

Blair was named to the Pro Bowl for 6 straight seasons (1977-85) and earned Associate All-Pro Honors in 1980. He won the NFC Central title and advanced to playoffs in 6 of his opening 7 seasons with the Vikings. Blair also played on the Super Bowl IX and XI teams. The Vikings inducted him into the Ring of Honor on October 25, 2012.