Knockhill's layout follows the trackbed of a disused mineral railway that served Lethans Colliery, closed in 1951, joined by service roads. The circuit opened in September 1974, with the first car race held on 18 May 1975. Between 1974 and 1983 the circuit had several owners who gradually developed its facilities. Derek Butcher became owner in 1984 and has overseen sustained investment that brought Knockhill to the level where it can host rounds of the major British car and motorcycle championships.
Knockhill has three layouts: the 1.300-mile International circuit with nine corners, the 1.000-mile National layout with ten corners, and a 0.300-mile tri-oval. All layouts are 10 metres wide with a total elevation change of 37 metres — significant for a track of this length, and a defining feature of the driving challenge.
A lap of the International circuit begins at the start line, which unusually sits at a different point from the finish line. Leaving the start, drivers crest the circuit's high point, pass under a pedestrian bridge, and then brake hard for Duffus Dip — a fast, blind, downhill right-hand corner widely considered one of the most demanding corners in the United Kingdom. Following Duffus Dip are Leslie's, a quick left-hander at the foot of the descent, and McIntyre's, a ninety-degree right-hand bend with a tricky braking zone.
After Butcher's, the track dips to its lowest point before rising steeply to the Chicane. The second element of the Chicane is completely blind, and the inside sausage kerb means cars frequently crest on two wheels. Clark's follows, a blind uphill right-hander that regularly pitches cars onto two wheels, and then Hislop's — a left-handed kink at speed along the line of the old railway. The final corner, Taylor's hairpin, is one of the tightest in the UK, with an uphill apex offering the circuit's primary overtaking opportunity. Cars accelerate hard up the partly uphill pit straight to the finish.
The circuit hosted a round of the British Touring Car Championship for twelve years until 2002, when the promoters sought infrastructure upgrades. Knockhill made the required improvements and the BTCC returned in 2004 with live ITV television coverage. The British Formula Three Championship and British GT Championship also returned to Knockhill in May 2005. In 2008 the circuit named Leslie's Bend in honour of racing driver David Leslie, shortly after his death in a small jet-aircraft accident at Farnborough.
In 2012 Knockhill restarted racing and track days in the anti-clockwise direction, becoming the first racing circuit in the UK in modern times to gain a licence for both cars and motorcycles to compete in both directions.
Beyond the main circuit, Knockhill operates a concrete rally stage, a 500-metre karting circuit east of the main paddock, a skid pan, and an off-road course in the infield that was reprofiled for Rallycross events in 2019. The circuit offers driving experiences in road and race cars and provides motorsport taster days for people with disabilities.
Annual highlights include rounds of the British Touring Car Championship and British Superbike Championship, along with Scottish Motor Racing Club and Knockhill Motor Sports Club events and Super Lap Scotland sessions.
Knockhill appeared in Episode 7 of Series 8 of Top Gear and in the first episode of Idris Elba: No Limits. The circuit was also the location for Kaiser Chiefs' "Hole in My Soul" music video. It features in Project CARS 2, Colin McRae: Dirt, several games in the TOCA series, and iRacing, where its tight, undulating layout presents sim racers with the same blind-crest and elevation challenges that define the physical circuit.