A left-handed pitcher, he spent all or parts of 13 seasons (1960–72) in Major League Baseball as a member of the Pittsburgh Pirates, San Francisco Giants, Cincinnati Reds and Houston Astros.

In 1959, his third minor league season, he won 16 of 25 decisions for the Triple-A Columbus Jets, posted a strong 3.22 earned run average, and hurled 11 complete games and four shutouts in 28 starting pitcher assignments.

When he returned to the Pirates in June 1969, he pitched out of the Pittsburgh bullpen through 1970, appearing in two games of the 1970 National League Championship Series against Cincinnati and working a total of one-third of an inning.

Released at the end of October, Gibbon joined the Reds in 1971 and posted a 2.94 ERA and tying his career-best mark for saves with 11.

During his MLB career, Gibbon compiled a 61–65 record with a 3.52 earned run average and 743 strikeouts in 1,1192⁄3 innings pitched; he allowed 1,053 hits and 414 bases on balls.