Born in Edinburgh, Shedden began racing in the Ford Fiesta Championship in 1999 with Tim Norton Motor Services Ltd. Racing Team, www.timnortonnmotors.co.uk, and won it the following season with 9 wins. He raced in the SEAT Cupra Championship, finishing as runner-up in 2003 and 4th in 2004. He also made a one-off appearance in the Production Class of the BTCC at Knockhill in 2001, and at the same circuit in the Porsche Carrera Cup Great Britain in 2005. He was entered in the 2002 BTCC by GR Motorsport in an Alfa Romeo, but this never reached the track. He has worked as Business Development Manager for the Knockhill circuit, alongside his wife Jillian. He has raced at Macau several times.

For 2006, Shedden was chosen by Team Halfords to drive for them in the BTCC, alongside reigning series champion Matt Neal, noting that “it’s brilliant to have a teammate that I can learn so much from”. He took his first win in the series in race 7 at Oulton Park, and added another in round 10 at Thruxton, where he also took his first pole position. He finished 4th overall with five wins in 2006, finishing the season as rookie of the year. In 2007 his team switched to the Honda Civic, and again took four wins. He was again 4th overall ahead of Neal.

In 2008 he was the team leader alongside Tom Chilton, with Neal leaving to join VX Racing. He took a 2nd place in the season opener, but crashed heavily in race 3. He did not achieve a podium finish at Donington Park, and at Thruxton he led races 1 and 3, but suffered punctures on lap 8 of both races. He was placed in 7th in the Drivers Championship.

Halfords returned as the team’s main sponsor for 2016 a full 10 years since they took Matt Neal to his second drivers title. Shedden hit the ground running with a win at the first round. However a lean spell mid season due to some bad luck saw Shedden sitting 9th in the standings at the halfway point. In the second half of the season Shedden would take 3 wins and 4 podiums to claw back the points deficit to BMW’s Sam Tordoff. In the last race of the season Shedden overtook Sam to clinch his third championship title. Shedden became the first man to successfully defend his crown since Fabrizio Giovanardi in 2008.

2009 saw Shedden joined at Team Dynamics (previously Team Halfords) by former Luton Town F.C. Chairman, David Pinkney. He also took on a new role as Team Ambassador for new racing team, YourRacingCar.com who contested their first year together in the BTCC support series, the Ginetta G50 Cup. He was ranked 9th in the Drivers Standings but was later replaced by James Thompson.

On 15 April 2009 it was announced that James Thompson would be replacing Shedden in the Team Dynamics car for the remainder of the 2009 season. The team said it was working on funds for a 3rd car for Gordon to run later in the season. However, before the round at Snetterton Shedden was signed by Clyde Valley Racing. After competing at two events for the team, they withdrew from the rest of the season. After missing the Silverstone round, Shedden rejoined the series at the penultimate round with the same bio-ethanol SEAT León that he raced for CVR, under the Club SEAT banner. Despite all the changes Shedden managed 2 podiums during 2009 and finished up in 12th in the Drivers Standings.

Shedden stayed with Honda in 2012, driving the new full-NGTC Honda Civic. His teammate would Matt Neal for the third year in a row. He had a disappointing opening round at Brands Hatch, his car was plagued with electrical problems for much of the weekend. He was disqualified from the third race of the day after his team worked on his car during the red flag period. Things improved at the next round where Shedden took two wins from three races, including one inherited due to penalties for Mat Jackson and Jason Plato. Problems for Plato at Oulton Park and good results put him in the championship lead after the first race. He was second in the championship going into the summer break, one point behind team–mate Neal. When the season resumed at Snetterton, Shedden’s car caught fire in the first free practice session. Shedden finished third in race three but post-race scrutineering found that his Honda had been over-boosting, thus disqualifying him from the results. He won two of the three races at Rockingham in wet conditions where he regained the championship lead. Shedden secured his first BTCC title in race two at Brands Hatch, finishing second behind Aron Smith.

2014 saw the Honda team make the switch to run the new Honda tourer model for a year. It happened to be fairly unsuccessful however. Shedden managed two wins, 8 podiums and finished up 3rd in the drivers championship.

for 2015 the team ran a pair of brand new Honda Type R’s. Shedden took the cars first win in just the second race of the season. In what was to be one of the most tense and dramatic title showdowns ever. Shedden took the title by just 4 points from Jason Plato and thus his second drivers title.

In January 2018, Shedden announced his departure from Team Dynamics, stating he was moving onto “pastures new”. It was later announced that he would switch to the World Touring Car Cup championship, driving for the W Racing Team Audi works team. In December 2019 the WRT team announced it will not be running in 2020 in the World Touring Cup leaving Gordon without a seat.