In a photo finish to decide the other two medals, Martin Loewstroem Nyenget took silver and Harald Oestberg Amundsen the bronze as they edged out fellow Norwegian Jan Thomas Jenssen and Italy's Federico Pellegrino.
All of the 28-year-old Klaebo's previous 10 world championship golds came in either sprint or relay events and though he was pushed by a chasing group that never let him break away, he kept his cool to accelerate out of the final bend to win in a time of 44 minutes 22.3 seconds.
Overnight rain and relatively warm temperatures provided a challenge for both the organisers and the waxing teams tasked with preparing the course and the skis respectively as thousands of fans turned out to watch.
After a tight first 10km, Hugo Lapalus of France was first out after the switch from classic to freestyle skis but the chasing pack were hot on his heels, and by the 13km mark only seven seconds separated the leading group of 14 racers.
Klaebo played his hand cleverly, sticking close to the front and allowing others to set the pace while probing for a breakaway, but he was never offered a chance to launch one of his trademark uphill spurts.
As a result, he had to wait until the race reached its climax in the ski stadium. Roared on by the fanatical home spectators, he expertly navigated the final two bends before turning on the afterburners on the home straight and surging to the finish, saluting the crowd as he triumphantly crossed the line.
