Born and raised in Southern California, Allyson hails from a close-knit family in the Los Angeles area. Her father, Paul, is an ordained minister who teaches New Testament Greek at the Master's Seminary in Sun Valley, while her mother, Marlean, is an elementary school teacher. Older brother Wes is a very talented sprinter himself (personal bests of 10.27 and 20.43), and has encouraged Allyson throughout her track & field career.

Allyson has long shown the kind of potential which she is now only beginning to fulfill. She began running in her first year of high-school, after being inspired by her brother's efforts in track and field events, and hasn't looked back since.

After a whirlwind 2003 season when she was just 18 years old (where Allyson ran the fastest 200m by a junior woman in the history of track and field), Allyson has now established herself as one of the most versatile sprinters in the world today.

Looking back to the time of the 2000 Olympics in Sydney, Allyson was a little-known high school sprinter in the Southern California area. Her biggest race of that year was the 200m at the California High School Championships (a stark contrast to the Olympic Games!). She finished 5th in that race with a time of 24.35 - not bad for a 14-year old in their first year of athletics! But there was evidently more to come.

At the same championships the following year, Allyson won the 100m and placed 2nd in the 200m. From there, she went on to win the 100m title at the World Youth Championships - a gold medal in her first international major championships. Just a taster of what was in store in the near future.

In 2002, Allyson broke all of her personal bests by considerable margins, and people started to take notice of this newly-emerging young sprint talent. The inevitable comparisons to Marion Jones had already started. Allyson broke 23s for the first time, and even ran a wind-assisted 22.69! Her wind-legal best of the season (22.83) was the fastest by a US junior that year, qualifying her for the World Junior Championships team. Although finishing in 5th place there (despite having to deal with niggling injuries throughout the year), it all provided invaluable international championship experience for Allyson - something that she was to soon get used to.

In many ways 2003 was very much a 'break-out' year for Allyson. She finally acheived what everyone had been suggesting she might do - she broke Marion Jones' high-school record in the 200m. At the Mt. SAC relays, Allyson ran 22.51 to set a new high-school record. This was followed by a performance just a few weeks later that made the whole world take note. Running at altitude in Mexico, Allyson knew she had a good chance of setting a personal best. And she delivered - her winning time of 22.11 was declared a world junior record. It was only a week or so later that Allyson discovered her record wasn't going to be ratified because the meet didn't conduct drug testing (a criteria for accepting world records). Still, this wasn't much of a set-back, as she knew she was capable of setting the record again.

Finishing 3rd at the US Championships in 2003 qualified Allyson for a spot on the World Championships team. However, before the World Championship meet, Allyson competed at the Pan-American Games and won a bronze medal in the 200m. By the time she had reached the World Championships, she'd already competed in over 30 races that year, so it almost came as no surprise when she failed to reach the finals. Not that it bothered Allyson too much - the Olympics were a bigger goal and were just 12 months away.

2004 saw a change of coach (to Pat Connolly) and a modified racing program, geared towards the Atlanta Olympic Games. Of course, she had to get through the 2004 US Championships first, but this never really presented a problem. She won it in convincing style with a time of 22.28 - her fastest since her 22.11 the year before. Suddenly, she was emerging as a medal favourite for the Olympic Games.

Winning her heat, quarter-final and semi-final in Athens, Allyson was always very much in the hunt for medals at the Olympics. Lining up for the final however, there was a very real threat in the lane outside of her in the form of Veronica Campbell (double World Junior Champion, with an unbeaten streak over 200m dating back to 2000). Unfazed by Campbell, Allyson ensured she ran her own race to the best of her capabilities. Although she finished 2nd to Campbell in the final, Allyson's silver-medal-winning 22.18 was undoubtedly the best run of her career and is still the official World Junior record.

Felix became the youngest ever gold medalist sprinter in the 200 meters at the World Championships in Helsinki in 2005 and then successfully defended her title at Osaka two years later. At Osaka, Felix caught Jamaican Veronica Campbell on the bend and surged down the straight to finish in 21.81 seconds, lowering her own season-leading time by a massive 0.37 seconds. After the final she stated that "I feel so good, I am so excited. I have been waiting for so long to run such a time, to run under 22 seconds. it has not been an easy road, but finally I managed," said Felix. At that time, she addressed her future, saying, "My next goal is not the world record, but a gold in Beijing. I want to take it step by step. I might consider to do both -- the 200 and the 400 meters -- there." In 2007, Felix became only the second female athlete; after Marita Koch in 1983 to win three gold medals at a single IAAF World Championships in Athletics.

Felix continues to lift and press heavy weights as part of her training routine. Currently Felix can leg press 700lbs despite her size.

Felix fully qualified for the 2008 Olympic Games during the 2008 Olympic trials in the 200 metre, but just missed qualifying for the 100 metre. However, at the 2008 Summer Olympics in Beijing, despite running her season's best time in the 200 metres, Felix again finished second to Campbell, who ran 21.74 to clinch the gold medal. Felix also ran the 400 meters, but only as a member of the U.S. women's relay team in that event. The team finished first, giving Felix her first Olympic gold medal.