In 1966, Bristol was named to the Reds' coaching staff, and when the team performed badly under rookie skipper Don Heffner, Bristol took over the club as manager on July 13. At 33, he was the youngest pilot in the Major Leagues that season through 1969. Bristol guided the Reds through 31⁄2 winning seasons, but he was dismissed following the 1969 campaign. Sparky Anderson, who took over from Bristol, would go into the Baseball Hall of Fame as the leader of the "Big Red Machine".
Cincinnati (298–265, .529) represented the highwater mark of Bristol's managing career. He would never manage another winning club.
Later struggles as MLB manager
Not long after being fired by the Reds, Bristol was hired by the Seattle Pilots as the second manager in their history. He walked into a very difficult situation; the Pilots were on the verge of bankruptcy, and went to spring training not knowing whether they would play in Seattle or Milwaukee in 1970. Just six days before Opening Day, the Pilots got word they would be moving to Milwaukee as the Brewers. The Brewers under Bristol were never able to put together a winning team; he was fired 30 games into the 1972 season.
In 1976, Bristol was hired as manager of the Atlanta Braves. Midway through the 1977 season, with the Braves mired in a 16-game losing streak, owner Ted Turner sent Bristol on a 10-day "scouting trip" and took over as his own manager. This only lasted for one game (a 2–1 loss to the Pittsburgh Pirates) before National League president Chub Feeney ordered Turner to give up the reins, citing major league rules which forbid managers or players from owning stock in a team.[2] After the Braves broke the streak with third-base coach Vern Benson as interim manager, Bristol—who had returned to his offseason home in Andrews, North Carolina—was brought back to finish out what was at the time the worst season in the Atlanta portion of Braves history (61–101—including a 60–100 record by Bristol). He was fired at the end of the season.[3] He last managed in MLB with the Giants late in the 1979 season and all of 1980 before he was replaced by Frank Robinson, prior to the 1981 season. In June 1980, Bristol got into a fight with Giants pitcher John Montefusco after a victory over the rival Los Angeles Dodgers. Montefusco was angry at Bristol for removing him from the game too early.[4] Bristol finished with a career managerial record of 657 win and 764 defeats (.462).
In addition to his rookie MLB season with Cincinnati, Bristol also served as the third-base coach of the Montreal Expos (1973–75) and Giants (1978–79), plus two terms with the Philadelphia Phillies (1982–85; 1988), and two additional stints with the Reds (1989; 1993).