The 21-year-old produced a stunning performance to lead from start to finish to win in 48.35 seconds with Turkey's Yasmani Copello.
The 21-year-old produced a stunning performance to lead from start to finish to win in 48.35 seconds with Turkey's Yasmani Copello taking second.
"I don't know how I feel man, I can't believe it," gasped Warholm.
America's Olympic champion and race favourite Kerron Clement took the bronze.
Warholm, a former decathlete, deployed similar tactics to his semi-final bursting from the blocks and tearing away with Clement content to run at the pace that has brought him two world titles as well as the Olympic gold.
The Norwegian, who was also Scandinavia's first world champion in the event, had tied up in the semi-final but this time he showed no signs of fatigue.
He came to the final hurdle with Clement having eased himself to within striking distance of him and looking dangerous.
However, it was the 31-year-old American who faltered when it mattered, stumbling over the final obstacle being passed by the fast-finishing European champion Copello and was fortunate to have just enough left in his legs to take third.
Warholm celebrated by donning a 'Viking helmet' on his lap of honour.