She became the first Nigerian World Record champion and gold medallist in the 100m hurdles.
Amusan, 25, started her feat on Saturday when she broke her African personal record of 12.41, she ran the race in 12:40 seconds.
The result means she has broken the African record three times in 10 months (12.42 seconds in Zurich, 12.41 seconds in Paris and 12.40secs in Eugene).
The Nigerian hurdler finished ahead of Jamaica’s Danielle Williams (12.87 seconds), Ireland’s Sarah Lavin (12.99 seconds) and Australia’s Celeste Mucci (13.01 seconds).
She then progressed into the semifinal to face reigning African Games and African Championships Alia Armstrong who recorded 12:48s.
But Amusan had no one to fear as she breezed past all of them in the semifinal to finish the race in 12:12s breaking another record set by Kendra Harrison (12:20s).
Now to the final stage, in the early hours of Monday morning, Amusan set to the track and made a new World record of 12:06s.
Her winning time will not be recognised as a world record, however, due to a strong following win of 2.5 metres per second.
Jamaica's Britany Anderson took silver in 12.23sec, while Olympic champion Jasmine Camacho-Quinn of Puerto Rico claimed bronze in 12.23.
"Honestly, I believe in my abilities but I was not expecting a world record at these championships," Amusan said after her final victory.
"The goal is always just to execute well and get the win.
"So the world record is a bonus. I knew I had it in me but I could not believe it when I saw it on the screen after the semis.
"Before the final, I just tried to stay calm and to do my best.
"I took a deep breath knowing that I have some goal to accomplish and it worked pretty good.
"I knew it was very fast but not this fast."