Gibson announced last year he had pancreatic cancer.
The legendary pitcher, who played all 17 seasons of his career with the Cardinals, was a nine-time All-Star, Gold Glove winner and two-time World Series champion.
He was inducted into the Baseball Hall of Fame in 1981, his first year of eligibility.
Focused and determined as he was, he scored two contracts after college with both the Cardinals and the Harlem Globetrotters before eventually deciding to stick with the former, according to MLB.
In 1968, Gibson won his first Cy Young and MVP awards after finishing the season with 22 wins, a major league record 1.12 ERA and 268 strikeouts. His dominant season in 1968 led MLB to lower the pitching mound the following year.
Gibson retired after the 1975 season as the Cardinals all-time leader in wins (251), strikeouts (3,117), shutouts (56), Games started (482) and complete games (255). The two-time Cy Young winner holds the record for most strikeouts in a World Series game (17) and in a World Series (35).
CNN’s Christina Maxouris contributed to this report.