Powell was born in Philadelphia, Pennsylvania. He attended Edgewood High School in West Covina, California, where he finished second in the High jump at the CIF California State Meet in 1981. He went on to attend the University of California, Irvine and later transferred to the University of California at Los Angeles. He is a member of Alpha Phi Alpha fraternity.
Powell won the Long jump silver medal at the 1988 Summer Olympics in Seoul.
At the 1991 World Championships in Athletics (Tokyo), Powell broke Bob Beamon's almost 23-year-old Long jump world record by 5 cm (2 inches), leaping 8.95 m (29 ft 4 1⁄4 in). Powell's world record, since August 1991, still stands, making Powell the fourth person since 1900 to hold the Long jump world record for over 20 years. His feat earned him the James E. Sullivan Award and BBC Overseas Sports Personality of the Year Award in 1991.
He also holds the longest non-legal jump of 8.99 m (29 ft 5 3⁄4 in) (wind-aided +4.4) set at high altitude in Sestriere, Italy in 1992.
Powell again won the Long jump silver medal at 1992 Summer Olympics in Barcelona. In addition to his famous 1991 victory, he won the Long jump again at the 1993 World Championships in Athletics, and came third at the 1995 World Championships in Athletics.
Powell competed in the 1992–93 Foot Locker Slam Fest and successfully dunked from the free throw line.
After the 1996 Olympics, Powell retired. He returned in 2001 with a goal of competing in the 2004 Olympics, but did not make the American team.
Powell became an analyst for Yahoo! Sports Olympic Track & Field coverage.
He stated in July 2009 that he intended to return to competition with the aim of breaking Tapani Taavitsainen's Masters over-45 world record in the Long jump.
Powell now coaches Long jump permanently at the Academy of Speed in Rancho Cucamonga, California.
At the Simplot Games on February 20, 2015 in an official announcement Powell stated that, at the age of 51, he would jump again in competition. On March 7, 2015 Powell entered the Athletics New Zealand Track and Field Championships, with every jump considered an attempt at the World Masters record. However, Powell sustained an injury in warm up and didn't actually compete. He later stated he will jump again in the future.
If he breaks the Masters record he will be the only athlete in any event to ever hold both the current World record and the World Masters record in such an old division simultaneously. Yuriy Sedykh held both the world record and the record in the M45 division from 2001 to 2010. Jonathan Edwards and Jan Železný currently have the achievement in younger divisions, Jarmila Kratochvílová should also, but her superior masters performance has never been recognized by World Masters Athletics. Haile Gebrselassie, Carlos Lopes and Jim Peters set both records simultaneously as 35-year-olds.
In July 2016 his daughter Micha Powell was officially named to Canada's Olympic team.