It was the 22-year-old's 16th gold medal at the worlds and added to her all-around world titles from 2013, 2014, 2015 and 2018.
American Simone Biles became the first woman to win five all-around titles at the gymnastics world championships in Stuttgart on Thursday, building on her legacy as one of the greatest of all time.
It was Biles' 16th gold medal at the worlds and added to her all-around world titles from 2013, 2014, 2015 and 2018.
Needing 12.301 in the floor exercise to reclaim her title in the final rotation, Biles scored 14.400 points to finish with an overall score of 58.999 -- beating China's Tang Xijing by a huge margin of 2.100.
Russia's Angelina Melnikova took bronze with 56.399.
"It means the world to me," Biles told reporters. "For my fifth, that's kind of unheard of so it was really exciting.
"But we finished strong and we gave it our all it's super exciting that we had the opportunity to do this."
Biles recorded two penalties on the floor but still managed to secure the biggest margin of victory at a world championships under the Code of Points - a scoring system that was introduced for major events in 2006.
A year ago in Doha, Biles competed with a kidney stone and started with a shocking fall on her vault routine, but there were no hiccups this time as she dictated the proceedings inside a packed arena.
The four-times Olympic gold medallist produced a massive Cheng vault, scoring 15.233 despite a 0.1 penalty for stepping out of bounds.
The second rotation saw her earn score a 14.733 on the uneven bars, considered her 'weakest' apparatus, but was still enough to hand her a lead of over one point.
Biles did not perform her eponymous double-double dismount off the balance beam, a skill widely thought to be under-valued in difficulty by the International Gymnastics Federation. Yet she still finished with a leading score of 14.633 on the apparatus.
It was her second world title of the week in Stuttgart, having already helped the US to their fifth consecutive team title on Tuesday.
The 22-year-old is now just one short of Belarusian Vitaly Scherbo's record haul of 23 medals - a milestone she could surpass by the end of the individual events at the championships this weekend.