Conigliaro was born in Revere, Massachusetts, and played high school baseball in nearby Swampscott. In the 1965 Major League Baseball draft—the first-ever MLB draft—Conigliaro was selected by the Boston Red Sox with the fifth overall pick, becoming the first player ever drafted by the team. Conigliaro played in the minor leagues during the 1965 to 1968 seasons, then made his MLB debut with Boston in April 1969. Conigliaro showed great promise as a hitter in his years in Boston, with 16 doubles and 18 home runs in 1970, and 26 doubles and 11 home runs in 1971. He finished 8th in the American League in doubles in 1971, his most productive year in the majors. In 1970, he was 10th in American League in being hit by pitches, with seven. His most memorable game may have been on July 4, 1970, when both Billy and his brother Tony homered against the Cleveland Indians. Conigliaro was part of a ten-player blockbuster that sent him, George Scott, Jim Lonborg, Ken Brett, Joe Lahoud and Don Pavletich from the Red Sox to the Milwaukee Brewers for Tommy Harper, Marty Pattin, Lew Krausse and minor-league outfielder Pat Skrable on October 10, 1971. Billy, who idolized his older brother Tony, had been highly critical of the Red Sox for trading his brother to the California Angels, especially after Tony's remarkable 36 home runs during the 1970 season after his famous "beaning" incident in 1967. Unhappy in Milwaukee, Conigliaro announced his retirement from baseball in the middle of the 1972 season. He came back to baseball in 1973 as a part-time player with the eventual World Champion Oakland Athletics, making brief appearances in that season's American League Championship Series and the World Series. Once again, Billy became disgruntled with ownership—this time in Oakland—and retired at the conclusion of that season. He attempted a comeback with Oakland several years later, but ultimately retired for good after being assigned to their Triple-A affiliate on what was to be a "temporary" basis.
Personal life
Conigliaro was an early pupil of Shotokan karate grandmaster Kazumi Tabata, who acknowledged Conigliaro in his book.
