Buckner elected to play college basketball for the Indiana University Hoosiers under Coach Bob Knight.

He ended his college career as a four-year starter and three-year captain at Indiana, and also played football for one year.

"The one thing that I learned early was to respect authority figures, right or wrong", Buckner told the Dallas Morning News concerning his relationship with Knight.

He played for the United States men's national basketball team in the 1974 FIBA World Championship, winning the bronze medal.

Although he scored only 10.0 points per game during his college career, Buckner was selected by the Milwaukee Bucks in the first round of the 1976 NBA draft, the seventh pick overall.

Before he joined the Bucks, Buckner played on the gold medal-winning 1976 U.S. Olympic basketball team alongside Adrian Dantley, Mitch Kupchak, and Scott May.

He was unspectacular offensively, averaging 8.6 points while shooting .434 from the field, but he excelled on defense, ranking fourth in the league with 2.43 steals per game.

The next year Buckner raised his scoring slightly, to 9.3 points per game, and was named to the NBA All-Defensive Second Team.

In 1979–80 he averaged 10.7 points and 5.7 assists, made the NBA All-Defensive Second Team for the second time, and helped the Bucks to the Midwest Division title.

Under Coach Don Nelson, Milwaukee had assembled a solid lineup that included forward Marques Johnson, center Bob Lanier, and guards Brian Winters, Sidney Moncrief, and Junior Bridgeman.

Milwaukee had high hopes for the postseason, but Julius Erving's Philadelphia 76ers derailed the Bucks in the Eastern Conference Semifinals.

He was never going to be a flashy player or a big scorer; his low-trajectory shot was jokingly said to have been responsible for more bent rims than Darryl Dawkins's dunks.

Milwaukee was trying to add a few essential parts that would turn the team into a championship contender, and the bottleneck at guard made Buckner expendable.

Boston, however, won a championship in 1984, with Buckner coming off the bench to spell Dennis Johnson and Gerald Henderson.

With the NBA championship ring, Buckner completed a Triple Crown résumé, one of only eight players in basketball history to do so.

In an interview with the Arizona Republic, Buckner repeated his success formula: "Dedication, commitment, extreme concentration, discipline, realizing it can’t be done alone, it has to be done through the team."

Believing that his young charges needed more discipline, Buckner determined from the start to be a stern taskmaster in Knight's mold.

[14] The plan backfired, with many of the players (including Jamal Mashburn) complaining publicly about Buckner's heavy-handed coaching style.