Bowsher was born in Harmony, Ohio. He graduated from Plattsburg High School in 1948 and served a year in the United States Navy in 1949. His introduction to racing came by attending an event, after which he committed to the sport full-time starting in 1949.
Bowsher joined the newly sanctioned ARCA Series in 1953, near the beginning of its existence. A decade later, in 1963, he delivered his most commanding season as a driver, accumulating 16 victories on his way to the ARCA championship. He defended the title in both 1964 and 1965, claiming three consecutive championships — a sustained run of dominance that cemented his status as the defining figure of the series in that era. His three driver championships, combined with the two he later won as an owner, gave the Bowsher operation a total of five ARCA titles.
Beyond ARCA, Bowsher competed in the USAC Stock Car Series in 1971, finishing second in the series standings and accumulating 21 wins in the category. As an owner, he won a USAC title in 1968 with A.J. Foyt driving, pairing the Ohio-based team with one of the greatest American drivers of the twentieth century.
Bowsher and Foyt were also among the first drivers to test stock cars at the Indianapolis Motor Speedway in the late 1960s, an experiment that preceded the track's eventual hosting of NASCAR events by decades. Bowsher's Ford won the 1976 24 Hours of Daytona in the stock car class, adding sports car endurance racing to a resume that already crossed multiple American open-wheel and oval disciplines.
Bowsher is credited as the first person to build a down-tube open-wheel modified race car, a design innovation that subsequently became standard in modern open-wheel modified racing. This contribution to chassis engineering extended his influence beyond his own driving and ownership record into the technical development of American short-track racing.
In 1988, Bowsher re-entered the ARCA Series as a car owner for his son Bobby. The father-and-son program produced 17 victories and two national championships. In 1989, less than a month before his 59th birthday and after approximately a decade away from the cockpit, Bowsher came out of retirement to substitute for defending ARCA champion Tracy Leslie at the Springfield Mile dirt oval. He qualified on pole and finished tenth while running on the lead lap — a performance that illustrated the depth of his craft even after years away from racing.
His son Todd also maintained a presence in the ARCA Series in subsequent years, extending the Bowsher family's connection to the series into a third generation of involvement.
Jack Bowsher died on April 8, 2006. He was survived by his wife Julie and five sons — Jack Jr., Gary, Jim, Bobby, and Todd — as well as a daughter, Jodie.
Bowsher's impact on American oval racing operated on three levels: as a driver who won three consecutive ARCA championships in the series' formative years, as an innovator whose chassis design influenced the structure of open-wheel modified racing, and as a team builder whose operation nurtured family talent across generations. His more than ten national titles across a 58-year career represent one of the widest footprints in grassroots American motorsport history.