Boyd had a long association with the University of Southern California's men's basketball, first as a player and then as its head coach. The 3-year letterman (1950–52) was USC's most valuable player as a senior in 1952. He then began his coaching career, first for five years in the high school ranks (at El Segundo, California and Alhambra, California), then for six years at the junior college level at Santa Ana College (his 1959 team finished second at the state tournament) and then collegiately, first at Seattle University, where he went 41-13 in 2 seasons (1964–65).
After a year out of coaching while working for Converse athletic shoes, he embarked on a 13-year career (1967–79) as head coach of the USC basketball team. His teams went 216-131 overall and played in the post-season four times (the 1979 NCAA playoffs, 1973 NIT and 1974 and 1975 Commissioner's Conference tourney). His 1971 team, which went 24-2 and was ranked fifth in the nation (USC was ranked first at midseason), is regarded among USC's best (he also won 24 games in 1974). His wins over UCLA in 1969 and 1970 were the UCLA's first losses in Pauley Pavilion, built in 1966. He was twice named the conference Coach of the Year. He sent ten players into the NBA, including Paul Westphal and Gus Williams.