Giro d'Italia winner Dumoulin became the first Dutch rider to take the men's individual TT title in style, winning over second-placed Primož Roglič (Slovenia) by nearly a minute.
It's Dumoulin's second gold medal of the 2017 Championships, having been part of Sunweb's team time trial winning team on Sunday. It's another victory for the Netherlands, too, after Annemiek van Vleuten took the women's time trial title on Tuesday.
British hope Chris Froome placed third at one minute and 21 seconds to round off a stand-out season that included the 2017 Tour de France and Vuelta a España victories.
The unusual course featured 28 opening kilometres of relatively flat terrain followed by the 3km climb of Mount Fløyen, featuring an average gradient of over nine per cent. It made pacing problematic, with several riders putting in a good time until the bottom of the climb, then fading.
Jan Tratnik (Slovenia) set down an early fast time of 46-24, the first rider to break the 40kmh average speed barrier. His time stood for a long period before Wilco Kelderman (Netherlands) bettered it with 46-15.
There followed a trio of riders who set very close times, with Nelson Oliveira (Portugal) clocking 46-09.52 to take the lead with Vasil Kiryienka (Belarus) and Gianni Moscon (Italy) within a second.
As the top-seeded riders got into their race, the intermittent times started to tumble. Dumoulin was third quickest through the first time check, and then fastest through the second.
Watch: Highlights of the elite men's time trial
Having threatened to rain all day, it wasn't until the final half an hour of racing that it started to fall and dampen the roads to provide an extra obstacle for the later starters.
Rohan Dennis (Australia) had started off very quickly, posting quick times through the time checks, but took a fall and lost time, ruling out his chance of the win. Nevertheless, he still managed to eventually finish eighth.
Meanwhile, Dumoulin kept going at his blistering pace, clocking the quickest times throughout the course and extended his lead out on the road. Froome was improving through each time check, but had left himself with too much work to do on the final climb.
Roglič finished with 45-38.79 to unseat Oliveira from the hot seat, but it was only temporary as Dumoulin completed his run in 44-41 to take the win with Froome third at 1-21 behind Roglič. Dumoulin's speed was such that he nearly caught Froome before the line.
Defending champion Tony Martin (Germany) came home for ninth place.
Great Britain's Tao Geoghegan Hart was a relatively late addition to the start list after Steve Cummings withdrew. The 22-year-old started well, but suffered a crash, scuffing up his right side and cutting his knee.
One of the most talked about aspects of the event was the provisional of a bike changeover area just before Mount Fløyen. Several riders had elected to swap time trial bikes for lighter road bike to tackle the ascent, and the UCI had provided an area in which to do this.
However, it wasn't long before the shortcomings of changing bikes were made clear as first rider off, Alexey Lutsenko (Kazakhstan) fumbled with his new bike after changing over, and received a push-off from his team helper that appeared to exceed the allowed limit shown by a red carpet laid onto the cobbles.
The advantage – or disadvantage – of swapping bikes may never be known. Dumoulin, Froome and Martin stayed on their TT machines throughout, but Roglič did make a change. In the end, it appeared to make little impact on the outcome.
The UCI Road World Championships continue on Friday, September 22, with the junior women's road race, followed by road races for the under-23 men, elite women (Saturday), junior men (Saturday) and elite men rounding off the championships on Sunday, September 24.
UCI Road World championships 2017, elite men's time trial, 31km
1. Tom Dumoulin (Netherlands), in 44-41.00
2. Primož Roglič (Slovenia), at 57.79 secs
3. Chris Froome (Great Britain), at 1-21.25
4. Nelson Oliveira (Portugal), at 1-28.52
5. Vasil Kiryienka (Belarus), at 1-28.75
6. Gianni Moscon (Italy), at 1-29.49
7. Wilco Kelderman (Netherlands), at 1-34.33
8. Rohan Dennis (Australia), at 1-37.39
9. Tony Martin (Germany), at 1-39.88
10. Jan Tratnik (Slovenia), at 1-43.45
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