As a track star at Sliver Creek High School he won back-to-back state championships in the 300-meter hurdles.  In 1979, while attending San Jose City College, he set a state record in the 400-meter hurdles and while competing for UCLA he won the NCAA title in the 400-meter hurdles.  At the 1988 Olympics in Seoul, he won a gold medal and set an Olympic record in the 400-meter hurdles with a time of 47.19 seconds.  He is considered to be the best combination hurdler in the history of track and field.

A champion on the high school, collegiate and Olympic stage, Phillips was inducted into the San Jose Sports Hall of Fame in 2003.