Collins attended Stanford University, where he was an All-American in 2000–01. In 2001, Collins was named to All-Pac-10 first team, and the National Association of Basketball Coaches (NABC) voted him to their third-team All-American team. He finished his college career ranked first in Stanford history for field goal percentage (.608) and third in blocked shots (89).

Collins was selected by the Houston Rockets with the 18th overall pick in the 2001 NBA Draft. In the 2002–03 NBA season, Collins took over the starting center role for the Nets and helped the franchise back to the NBA Finals. Collins has played for a number of NBA teams including the Grizzlies, Timberwolves, Hawks, Celtics, and Wizards.