The circuit measures 7.416 miles (11.935 km) in its original form, adjusted to 7.401 miles (11.911 km) with the addition of the Lindsay Hairpin for the 1965 season. The route uses a section of the B38 Hannahstown Road between Glenavy and Hannahstown, the B101 Leathemstown Road from Leathemstown Corner to Dundrod, and the B154 Quarterland/Tornagrough Road from Cochranstown to the B38/Upper Springsfield Road junction at the Lindsay Hairpin. The public roads are closed for racing, running through rolling Northern Irish countryside with the high-speed character typical of road circuits.
The circuit opened to competition in 1950 with the RAC Tourist Trophy for sports cars, an event that returned annually through 1955. The Ulster Trophy for Formula One and Formula Two machinery also ran at Dundrod from 1950 to 1953, bringing some of the leading single-seater competitors of the early 1950s to the Northern Irish public roads.
The RAC Tourist Trophy lap record was set by Mike Hawthorn in a Jaguar D-Type: 4 minutes 42 seconds at an average speed of 94.67 mph during the 1955 race. The race record belongs to the works Mercedes-Benz entry of Stirling Moss and John Fitch in a 300 SLR, who covered 84 laps (622.96 miles) in 7 hours 3 minutes 12 seconds at an average of 88.32 mph during that same 1955 event.
The 1955 Tourist Trophy was also the last car race held at Dundrod. Three fatalities during that event prompted the withdrawal of automobile racing from the circuit on safety grounds, citing the narrow and high-speed nature of the roads as incompatible with the cars of that era.
The Ulster Grand Prix transferred to Dundrod for the 1953 season when motorcycle racing left the Clady Circuit. From 1953, Dundrod hosted the Ulster Grand Prix as a round of the FIM Motorcycle Grand Prix World Championship, giving it a place in the premier international motorcycle racing calendar. The circuit's place in the World Championship continued until 1971.
The 1971 Ulster Grand Prix holds particular historical significance. Australian Jack Findlay won the 500 cc class aboard a Suzuki, which was notable as the first 500 cc class victory for a motorcycle powered by a two-stroke engine. That race was also the last Ulster Grand Prix to count as a World Championship round before the event's removal from the calendar.
Since 1971 Dundrod has continued as the home of the Ulster Grand Prix as a standalone road racing event outside the world championship structure, maintaining its place alongside the Isle of Man TT and North West 200 as one of the core events in the Irish road racing calendar.
The official lap record for the Dundrod Circuit is 3 minutes 15.316 seconds, set by Peter Hickman riding a BMW S1000RR during the 2019 Ulster Grand Prix.
Dundrod represents a specific tradition of road racing rooted in Northern Ireland's motorsport culture. Its high average speeds, public-road surface, and the permanence of the Lindsay Hairpin modification made over half a century ago illustrate a circuit frozen in much of its character since the mid-twentieth century. The departure of automobile racing after 1955 and the exit from world championship status after 1971 left the circuit as a preserve of the road racing community, where it has remained one of the fastest and most demanding circuits on which motorcycle racing is held anywhere in the world.