[4] As a junior in 1957, he recovered a fumble, delivered a key block on Notre Dame's touchdown, and was the leading rusher in a 7–0 victory that broke Oklahoma's record 47-game winning streak.

"[8] He also led the NFL with an average of 5.9 rushing yards per carry and won the 1959 National Football League Rookie of the Year Award.

[11][12] For the 1960 season, he rushed for 872 yards, a Lions single-season record and the fourth highest total in the NFL that year.

[1][13][14] In 1961, Pietrosante rushed for 841 yards, again the fourth most in the NFL, and was selected to play in the Pro Bowl for the second consecutive year.

[15] In September 1966, shortly before the start of the 1966 NFL regular season, the Lions' head coach Harry Gilmer placed Pietrosante on waivers.

[20][3][21] In February 1988, Pietrosante died of prostate cancer at Beaumont Hospital in Royal Oak, Michigan, at age 50.