Gardener was born in Bath, Somerset to a Jamaican father and British mother, and started his career at the World Junior Championships in 1994, where he was placed second in the individual 100 m and bettered this to take his first gold medal as part of the 4 × 100 m relay team. Joining the senior ranks, and coached by Malcolm Arnold for his entire career, Gardener took another silver in the 60 m, at the European Indoor Championships of 1998. He was not chosen for the relay team, which took gold. In 1999 he took bronze at the World indoors in the 60 m, breaking the British record. and later that year saw him run 9.98 s breaking the 10 second barrierfor the first time in the 100 m. He was also part of the national record breaking 4 × 100 m relay team along with Darren Campbell, Marlon Devonish, and Dwain Chambers that they set in Seville, Spain running 37.73 seconds. 2000 saw Gardener go one better in the European indoor 60 m taking gold as well as breaking the national 50 m record with a time of 5.61 s. Unfortunately he became injured during the summer and although making it to Sydney for the Olympics he did not progress through the early rounds. He retained his European indoor title in 2002 as well as a 4 x 100 mCommonwealth Games gold medal. 2003 saw another World indoors bronze despite being hampered by a hamstring injury but the following year he bettered this to take the gold, his first world individual title ahead of the fancied Shawn Crawford of the USA. Gardener made the squad for the 2004 Summer Olympics where he competed in the 100 m and won the gold medal in the 4 × 100 m relay with Darren Campbell, Marlon Devonish and Mark Lewis-Francis in a 38.07 s, their season's best and a narrow upset win over the United States. In March 2007, Gardener won his fourth European Indoor 60 m gold after fears that he may have to miss defending his title as his wife, Nancy, was due to give birth. Gardener's last professional race was a 4 x 100 m relay at the London Grand Prix at Crystal Palace on 3 August 2007. His team failed to finish this race. On 17 October 2013 it was announced that Gardener would take part in the 100m Sprint for Faith organised by the Pontifical Council for Culture and the Italian Sports Centre, as part of the Catholic Church'sYear of Faith.
Gardener has also won four senior national titles indoors and two outdoors.
Bobsleigh
In 2008 Jason took part in a project to qualify four athletes from diverse sports in the British 2 Man Bobsleigh Championships, after just two weeks of training. Along with World Champion track cyclist Craig MacLean, Rugby World Cup winner Dan Luger and Commonwealth Decathlon champion Dean Macey, he attempted to complete two runs down the course at Cesana Pariol in Italy to gain qualification to the finals. Selected as pusher for driver Macey, he succeeded in finishing in sixth place overall, as well as being the highest placed novice pair. The story was filmed for the BBC and broadcast in February 2009. Jason declined an offer to try and qualify for the next Winter Olympics in 2010.
