Kolb was drafted by Pittsburgh out of OSU in 1969, and played with the Steelers from 1969 to 1981. Kolb did not start in any game during his first two years, but became the starting left offensive tackle in 1971, replacing Mike Haggerty, for all 14 games, remaining in that position until 1981, his final year, though in the final two years he shared time with Ted Petersen (1980) and Ray Pinney (1981). He played next to left guard Sam Davis (football player) from 1971 to 1979, Davis' final year. Overall, Kolb started at offensive tackle in 177 games and earned 4 Super Bowl rings, during the 1974, 1975, 1978, and 1979 seasons.
During his playing days, Kolb was widely regarded as one of the strongest men in the NFL and played like the strongest one, protecting Terry Bradshaw's blind side from his left offensive tackle position on pass plays and opening holes for running backsFranco Harris, Rocky Bleier, and John Fuqua. Like many of the Steeler players of the 1970s, Kolb had his own cadre of fans, known as "Kolb's Kowboys."
Kolb competed in the second and third annual World's Strongest Man competitions in 1978 and 1979, placing on a very good 4th rank in both years, while often defeating much heavier and stronger competitors in certain events.