The 31-year-old finished the 44.2km course in a time of 55:04 to take the gold medal, having set the fastest times at all but the first time check at 9.7km.
Roglič was untouchable, pacing himself perfectly over the climbs to pull away from all of his rivals over the technical and demanding Tokyo course.
Staggeringly, not a single rider was able to finish within a minute of Roglič, with a resurgent Tom Dumoulin (Netherlands) taking silver with a time 1:01 down on his Jumbo-Visma teammate.
Rohan Dennis (Australia), who looked in contention at the halfway point, was forced to settle for bronze, 1:03 down on the winner.
There was huge disappointment for Stefan Küng (Switzlerand), who missed out on a medal by less than half a second.
World time trial champion Filippo Ganna (Italy) was the fastest rider at the first check at 9.7km but the hilly parcours was too much for the Italian, who faded consistently throughout the race and was forced to settle for fifth on the day.
Another pre-race favourite, Wout van Aert (Belgian) came unstuck on the second lap and crossed the line in sixth.
There was no doubting Roglič and his performance, though. The two-time Vuelta a España winner came into the crash after crashing out of the Tour de France and finishing out of contention in the men’s road race on Saturday.
He set off like a train and was less than half a second down on Ganna at the first check. At that point, the top six riders at the finish were separated by less than 10 seconds but as the course unfolded the gaps started to increase.
At 15km, Roglič was less than a tenth of a second up on Van Aert, with Ganna, Kung, Dennis, and Dumoulin just a handful of second further back. By the end of the first lap, Roglič was over eight seconds clear of his closest rivals but the second lap saw the Slovenian pull away from the entire field.
At 37.1km, Dumoulin was closest at 42 seconds, while Van Aert had drifted out to a minute back. Dennis rose to second on the road but then dropped to fifth before recovering to take his second ever Olympic medal, while Dumoulin secured the same place from the 2016 Rio Olympics.
How it unfolded
The men rode two laps of the 22.1-kilometre circuit, which started and finished at the Fuji Speedway. It began with a 4km mostly downhill section out of the Speedway, followed by a long uphill grind to the first time check at 9.7 kilometres. A long descent took the riders back to the entrance of the Speedway, followed by a hard rolling section to the finish line.
The men rode in overcast and hot conditions, with the humidity at 95 per cent, in air that felt more like soup. They rode in three waves, with Canada's Hugo Houle setting the first benchmark time. Houle was in the hot-seat until Remco Evenepoel (Belgium) in the second wave finally displaced him.
Rigoberto Urán (Col) then bumped Evenepoel down five riders later, and the Colombian held the top spot until Dumoulin demolished his time by over a minute. Dumoulin, who shocked the cycling world by walking away from the sport before the start of the season, showed that he has regained his competitive fire by setting the fastest splits at every point, catching his 90 second man, Brandon McNulty (USA).
Unfortunately for Dumoulin, Roglič was having the ride of his life, catching both his 90-second man, Kasper Asgreen (Denmark) and three-minute man, Joao Almeida (Portugal).
Just showing how fast Roglič was, despite being caught, Asgreen still finished seventh. Roglič was the only rider to post a sub-56 minute time of 55:04.19 .
The final three riders to start - time trial specialist Küng, world champion Filippo Ganna, and road race silver medalist Van Aert - were never in contention for gold, but all had a chance at the other two medal spots, with Küng finishing fourth, Ganna fifth and Van Aert sixth.
Both Küng and Ganna were less then two seconds out of the bronze medal time. However, the day was Slovenia's, as they won their first ever gold medal in cycling, and their second medal of these Games after Tadej Pogačar's bronze in the road race.
|Pos.||Rider Name (Country) Team||Result|
|1||Primož Roglič (Slovenia)||0:55:04|
|2||Tom Dumoulin (Netherlands)||0:01:01|
|3||Rohan Dennis (Australia)||0:01:03|
|4||Stefan Küng (Switzerland)||0:01:04|
|5||Filippo Ganna (Italy)||0:01:05|
|6||Wout van Aert (Belgium)||0:01:40|
|7||Kasper Asgreen (Denmark)||0:01:48|
|8||Rigoberto Uran (Colombia)||0:02:14|
|9||Remco Evenepoel (Belgium)||0:02:17|
|10||Patrick Bevin (New Zealand)||0:02:20|
|11||Alberto Bettiol (Italy)||0:02:33|
|12||Geraint Thomas (Great Britain)||0:02:42|
|13||Hugo Houle (Canada)||0:02:52|
|14||Stefan De Bod (South Africa)|
|15||Maximilian Schachmann (Germany)||0:03:29|
|16||João Almeida (Portugal)|
|17||Rémi Cavagna (France)||0:03:34|
|18||Maciej Bodnar (Poland)||0:03:42|
|19||Nikias Arndt (Germany)||0:03:45|
|20||Aleksandr Vlasov (Russian Federation)||0:03:51|
|21||Nelson Oliveira (Portugal)||0:03:55|
|22||Tanel Kangert (Estonia)||0:04:01|
|23||Tobias Foss (Norway)||0:04:47|
|24||Brandon McNulty (United States Of America)||0:04:53|
|25||George Bennett (New Zealand)||0:05:24|
|26||Michael Kukrle (Czech Republic)||0:05:37|
|27||Richie Porte (Australia)||0:05:49|
|28||Nicolas Roche (Ireland)||0:06:18|
|29||Tao Geoghegan Hart (Great Britain)||0:06:40|
|30||Toms Skujins (Latvia)||0:07:00|
|31||Patrick Konrad (Austria)|
|32||Alexey Lutsenko (Kazakhstan)||0:07:17|
|33||Amanuel Ghebreigzabhier (Eritrea)||0:08:18|
|34||Lawson Craddock (United States Of America)||0:08:48|
|35||Saeid Safarzadeh (Iran)||0:10:10|
|36||Azzedine Lagab (Algeria)||0:10:17|
|37||Lukáš Kubiš (Slovakia)||0:11:21|
|38||Ahmad Badreddin Wais (Refugee Olympic Team)||0:13:36|
|DNF||Ion Izaguirre Insausti (Spain)|
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