The 21-year-old, a quadruple Olympic gold medallist, prevailed despite mistakes on three of the apparatus at the Aspire Dome in Qatar's capital.

She was good enough to top the podium despite those uncharacteristic errors and adds to the team title she has already won in Doha with her United States colleagues.

That title remarkably came after Biles had admitted herself to hospital overnight due to a kidney stone.

She showed no ill effects as she scored 57.491 to come home in front of silver medallist Mai Murakami of Japan who tallied 55.798. 

American defending champion Morgan Hurd, who won last year in Montreal with Biles absent, had to settle for bronze this time on 55.732.

Biles began with 14.533 on the vault as she sat after performing a new move that she debuted during the team competition.

Hurd managed 14.600 to lead after the first rotation.

The eventual champion then scored 14.725 on the uneven bars to take the lead from Hurd, and despite falling off the beam she still scored 13.233 and led with just the floor to go.

There, Biles scored a massive 15.000 points despite stepping out on one occasion.

"This year has definitely had its ups and downs, going to therapy and other things besides," Biles said.

"Just being in the gym has been a little bit rough, but you try to focus on one thing at a time to get through it.

"I hope this gives confidence that you can still do well and not be penalised for it and for parents to put gymnasts in the sport and feel comfortable."

Men's and women's apparatus finals will begin tomorrow.

The men will compete on the floor, pommel horse and rings with the women on the vault and uneven bars.

Should Biles add another two golds to her total, she will become the first gymnast, male or female, to win 13 world titles.