The 22-year-old Reilly, whose trailblazing two-wheeled stunts have earned him a huge online following, pulled every trick out of the bag to nail his second run to score 95.80.
With several of the sport's biggest names still to complete their final two 60-second runs, Gateshead's Reilly then had an anxious wait to see whether or not the world title was his.
A rain shower prolonged the agony as organisers dried the track, with just Australia's Olympic champion Logan Martin and 2022 world champion Rimu Nakamura still to ride their second attempts around the circuit.
The 29-year-old Martin was already assured of a bronze and produced a sensational second ride but was unable to dislodge Reilly from the top of the leaderboard, settling for silver.
Britain's reigning Olympic champion Charlotte Worthington was in action in the women's competition later.
Persons:
Kieran Reilly, Australia's Logan Martin, Nick Bruce, Read, Britain's Kieran Reilly, Reilly, Gateshead's Reilly, Logan Martin, Rimu Nakamura, Nakumura's, Martin, It's, Britain's, Charlotte Worthington, Martyn Herman, Ken Ferris
Organizations:
Cycling, UCI, Glasgow Green, Olympic, Thomson
Locations:
Glasgow, Scotland, Britain, GLASGOW, United States