After graduation, Grabowski was selected in the first round of the 1966 NFL Draft by the Green Bay Packers, with the ninth overall selection. (Grabowski was also taken as the first overall pick in the 1966 American Football League Draft, by the Miami Dolphins.) Grabowski went on to play five seasons for the Packers, and was known as one football's "Gold Dust Twins" (along with team mate, Donny Anderson) in the late sixties. Grabowski finished his professional career by playing a single season for the Chicago Bears in 1971. Over his six seasons in the NFL, Grabowski rushed for 1,731 yards and scored 11 touchdowns (8 rushing, 3 receiving).