Sykes credits his grandfather Peter Brook, who loaned him a 600cc Ninja for a race weekend and financed his first steps in the sport. He raced in the British Supersport Championship from 2003 to 2006, finishing as runner-up to Cal Crutchlow in his final Supersport season in 2006.
Sykes made his British Superbike Championship debut in 2007 with the Stobart Vent-Axia Honda team alongside 2003 series champion Shane Byrne, finishing sixth overall. He demonstrated front-running pace with two podiums at Croft and pole positions at Oulton Park and Donington Park. In 2008, racing for the Rizla Suzuki team, he took pole at Oulton Park, won two consecutive races there, and added a third straight victory at Knockhill, ultimately finishing fourth in the championship with 316 points — just two points behind Cal Crutchlow.
Sykes made his World Superbike debut as a wildcard at Brands Hatch in 2008, qualifying sixth and delivering performances that earned him a factory contract with Yamaha Motor Italia for 2009. The Yamaha year proved difficult as teammate Ben Spies ran at the front while Sykes was largely mid-field, and Yamaha did not extend his deal.
He moved to Paul Bird Motorsport's Kawasaki team for 2010, and despite an uncompetitive machine, showed enough promise to earn a longer-term relationship with Kawasaki. In 2011 he came agonisingly close to the championship, finishing runner-up to Max Biaggi by just half a point. In 2012 he again finished runner-up, this time behind Biaggi in the Roman Emperor's final championship season.
The championship came in 2013, when Sykes secured the title with the third-place finish he needed at Jerez — a popular and long-deserved victory for a rider whose qualifying speed had long been regarded as exceptional. He marked his campaign with his 21st career Superpole at Misano in June 2014, one of many records he continued to accumulate on Kawasaki machinery.
Sykes remained with Kawasaki Racing Team until the end of 2018, when both parties agreed to part ways after his fourth-place championship finish that year. He signed with Shaun Muir Racing to ride BMW machinery from 2019, but was dropped mid-season in 2021 when Scott Redding was contracted for 2022. He returned to British Superbikes with Paul Bird Motorsport on a Ducati in 2022, finishing twelfth. For 2023 he returned to World Superbikes with a satellite Kawasaki team.
When Motorcycle News reviewed his WorldSBK statistics in early 2022, they recorded 34 wins, 114 podiums, and 51 pole positions from 349 races. His pole position record in the series surpasses all other riders in championship history. He also ranks second to Troy Corser in total career race starts.
Tom Sykes is remembered as one of the most complete qualifiers the Superbike World Championship has ever seen — a rider capable of extracting the absolute maximum from a motorcycle over a single flying lap. His 2013 title with Kawasaki was the culmination of years of near-misses and represented a high point for both the rider and the Japanese manufacturer in the modern WorldSBK era.