He is the current solo-machine lap record holder for the Snaefell Mountain Course set during the 2016 Senior TT in a time of 16 minutes 53.929 seconds at an average speed of 133.962 mph (215.591 km/h). Dunlop was the first rider in the history of the Isle of Man TT to achieve a lap of the course in under 17 minutes.
Widely regarded as one of the most tenacious competitors in motorcycle racing, Dunlop's aggressive style and pugnacious attitude has led to confrontation with organisers, race teams, fellow competitors and even on occasion, his brother William.
He made his TT debut in 2007, where his best finish was 25th in the Superbike TT. He made the decision to ride in the 2008 races at the last minute after the death of his father at the North West 200 earlier in the year. He finished 10th in the Senior TT with a fastest lap of 124.773 mph, making him the fastest Dunlop around the TT Course. Dunlop joined his father and uncle Joey in the record books in 2009 when he won the Supersport TT race on a 600cc Yamaha.
At the start of the 2015 Road Racing season, Dunlop had a poor start with race team Milwaukee Yamaha, and during the practice week of the 2015 Isle of Man TT, he dramatically left Yamaha to rejoin his previous team, BuildBase BMW, in order to give him the best chance of a good result.
Dunlop has also won at the North West 200, recording his only victory to date at the 250 cc race in 2008. His father was killed during practice for this event.
Dunlop took part in the Classic Superbike race at the Manx GP on Friday 31 August. He took the win in the Classic Superbike race at the Manx Grand Prix 2012. This was his sixth title on the Mountain Course and his third Manx Grand Prix race win following his debut, and victory, in the 2006 Newcomers MGP race. During the two-week 2012 Manx GP Dunlop worked in the pits for a team in the 600 Junior Race.
In February 2016, it was announced that Dunlop would again ride BMW in the Superbike class at International road races during the 2016 racing season, provided by Hawk Racing. The announcement was made at the MCN Motorshow at the Excel, confirming that Dunlop will be riding the 2016 BMW S1000RR.
Dunlop opened his account at the 2016 Isle of Man TT Races in the Superbike race, which he led from start to finish. Astride a BMW S1000RR, Dunlop bettered the existing absolute course speed record attained during one-lap, also setting a new average speed for the six lap race of 130.306mph in a race-record time of 1 hour, 44 minutes, 14.259 seconds for the 226 miles of racing.In addition Dunlop also won the prestigious John Williams Trophy.
Dunlop's second race of the week was the Supersport Junior 600 TT, race 1. The opening lap saw him dicing at the head of the field with Ian Hutchinson. By the end of the four-lap race, Dunlop finished in second place behind Hutchinson. Following routine post-race inspection of the machines, Dunlop's bike was deemed to have infringed race regulations with non-standard parts, and he was subsequently disqualified. Dunlop returned to the start line for the second race of 6 June, the Superstock TT on a 1000 cc BMW. However, handling difficulties contributed to him retiring from the race at the end of the opening lap.
In the second of the two Supersport Junior races, Dunlop finished second to Hutchinson. For the last race of Dunlop's schedule on Friday 10 June, he led the six-lap Senior TT from lap one, extending his lead over runner-up Ian Hutchinson, winning with a 31-second margin, raising his own absolute lap record speed previously set on Saturday, 4 June by a small amount, and setting a new race record time.
During the 2016/2017 closed season there were various rumours of possible proposals for 2017. After Hawk Racing's switch from BMW to Suzuki for 2017, Dunlop signed for the Bennett's Suzuki Racing Team campaigning the new Suzuki GSX-R1000 as part of a four-man squad. Dunlop will concentrate on International road races with team mates Sylvain Guintoli and Taylor Mackenzie in British Superbikes and Richard Cooper in National Superstock 1000.
After an introduction to the new machine at Mallory Park, Dunlop pre-season tested with teammates at Circuito de Velocidad de Cartagena and Almeria in Spain for five days. This was followed by a further work up at Donington Park on 22 March.
The qualifying week for the 2017 Isle of Man TT was plagued by poor weather. Following a sporadic week of qualifying the first race day was given over to additional qualifying and practice, which meant the curtain raiser to the meeting, the Superbike TT, was postponed for 24 hours.
Racing got underway on Sunday, June 4th. Dunlop formed up on the grid at the TT Grandstand on board the Bennett's Suzuki in what were ideal conditions. Setting the early pace, Dunlop crossed the line at the head of the field at the end of lap 1, posting a time of 17 minutes 15.79 seconds from a standing start, clocking and average speed of 131.135 mph (211.041 km/h). Going into the second lap with a slender 1.8 second lead over Dean Harrison, Dunlop continued to head the field until he was forced to retire at Handley's Corner.
Supersport (Race 1)
In the opening Supersport race, Dunlop took his place on the grid astride his familiar MD Racing Yamaha. Dicing for the lead with James Hillier at the end of the opening lap, Dunlop came into the pit stop at the end of lap 2 with a 2.75 second lead. Taking another second from Hillier at the end of lap 3, Dunlop continued to edge ahead on the final lap, coming home with a winning margin of 12.5 seconds.