Amateur and minors Zahn played for
Toledo DeVilbiss High School and the
University of Michigan. He was selected by the
Los Angeles Dodgers in the fifth round of the January
1968 Major League Baseball draft. After signing with the Dodgers, he played in the minor leagues for six years before making his major league debut on September 2, 1973. Zahn served in the
Washington Air National Guard as a member of the
141st Air Refueling Wing. He reached the rank of
staff sergeant at least.
Major leagues During his major league career, Zahn pitched with the
Los Angeles Dodgers and
Chicago Cubs of the
National League and the
Minnesota Twins and
California Angels of the
American League. Geoff won ten or more games for six consecutive seasons (1977–82) with the Twins and Angels, totaling 81 wins over that span. Zahn's best season came in 1982 when he compiled an 18–8 record, helping the Angels win the
American League Western Division crown. Zahn was selected as the left-handed pitcher on the
Sporting News AL All-Star Team after the 1982 season. ==Coaching career==