Phillips was a promising
sprinter in his early days, but concentrated on the
triple jump while at
University of Kentucky, before switching to the long jump after moving to
Arizona State University in 2000. He competed at
2000 Sydney Olympics and finished eighth in the long jump with a jump of 8.06 m. He was the best American performer in the event. At his first
World Championships he again finished eighth, after sustaining a hamstring tear.
He came to prominence in 2003, when he won both the
IAAF indoor and outdoor
World Championships. The indoor championship event was a close contest, with Phillips only beating
Yago Lamela by a centimeter. He won the outdoor title with a winning margin of four centimeters over
James Beckford of
In the run up to the
2004 Athens Olympics, Phillips was ranked number one in the world, and he won the
gold medal by a margin of 12 cm over his compatriot
John Moffitt. His winning jump of 8.59 meters was the fourth biggest in Olympic history, after
Bob Beamon (1968) and
Carl Lewis (1988, 1992).
His success continued at the next two World Championships. Taking the gold medal at the
2005 Helsinki event, and winning
Osaka two years later.
Phillips finished fourth in the long jump at the U.S. Olympic Trials, meaning he would not compete at the Beijing Olympics and would not defend his Olympic title.
On June 7, 2009, Phillips won the long jump at the
Prefontaine Classic with a personal-best third jump of 8.74 m, defeating 2008 Olympic gold medalist
 A jump that put Phillips in the
all-time performers top 10, despite a 1.2 metres/second headwind. He won the US Championships later that month, giving him another chance to reach the podium at the World Championships.
2009 World Athletics Championships, in
Berlin, Phillips won the gold in the long jump with a jump of 8.54 m.
 He repeated the feat in
Daegu in 2011 with a leap of 8.45 m. During the championships in Daegu, Phillips was assigned the bib number 1111. After winning, Phillips proudly pointed to the number appropriate for finishing first in four championships.
A car accident just before the start of the 2012 outdoor season left him with back and neck injuries.
 Further to this, an Achilles tendon injury recurred and instead of preparing for the
2012 London Olympics, Phillips opted to undergo surgery to prolong his career.
At the 2013 World Athletics Championships, in Moscow, Phillips placed 11th in the long jump with a jump of 7.88 m and announced this was his last competition and retirement.