Campbell attended Morningside High School in Inglewood, California before playing college basketball at Clemson University. During his four years at Clemson, he averaged 15.3 points per game, 6.8 rebounds per game and 2.7 blocks. His college team was involved in one of the most notable plays in college basketball history – a one-point loss in the 1990 NCAA Tournament to a Connecticut team following a miraculous full-court catch-and-shoot play by Tate George with one second on the clock. That same year, the Los Angeles Lakers drafted Campbell with the 27th pick in the 1990 NBA draft.
Campbell's longest tenures were with the Lakers and the Hornets (in both Charlotte and New Orleans); he would also play with the Seattle SuperSonics and briefly for the New Jersey Nets, spending most of the final two seasons of his career as a member of the Detroit Pistons, being on roster in the 2004 NBA Championship team. During Campbell's tenure with the Pistons, perhaps his most important contribution was his defense against center Shaquille O'Neal in the two playoff series in which the Pistons engaged O'Neal's teams (against the Lakers in the 2004 Finals and against the Miami Heat in the 2005 NBA Eastern Conference Finals); because of his enormous bulk and strength, he presented a unique challenge to O'Neal in the low post and was one of the few NBA players who could pose a serious physical challenge to O'Neal on defense.
Campbell's 15-year career comprised 1,044 games, of which he started 671, and 106 playoff games, of which he started 53. In 15 seasons, Campbell averaged 10.3 points per game, 5.9 rebounds per game and 1.5 blocks. He was especially known for his shot-blocking ability, with 1,602 career blocks; he is 31st all time in blocks. Notably, Campbell was the Los Angeles Lakers' leading scorer in the 1990s. His nicknames were 'Easy', 'Big E', 'Big Homie' and 'The Janitor', which he received for his ability to clean up the boards.
Campbell was arrested for drunk driving in California in 1995.