The 28-year-old American is the most individual World Championship gold medalist in history in long course and now took her 17th, of which the sixth on 1,500 meters freestyle.
In total, with relay, she has 22 World Championship gold medals.
But her attack on her own seven-year-old world record failed.
In 1,500 meters, Ledecky kept world record pace – at most she was three seconds under – but in the end, she did not have the strength.
Love for 1,500
The time 15.26.44 was finally almost six seconds over the record.
I love this event. It was in this one that I set my first world record in 2013. There are many fine memories over the years, I'm glad I won here in Singapore, she says in the stadium interview.
Ledecky also has six World Championship titles on 800 meters freestyle and is, along with Sarah Sjöström, 50 meters butterfly, the ones who have won the most gold in the same event.
Sjöström won six in a row, a streak that is broken in Singapore as she will become a mother.
The margin of victory to the second-placed Simona Quadarella, Italy, became just over five seconds.
Ledecky took her first World Championship gold medals in long course in 2013, when she had already made her Olympic Games debut the year before in London and as a 15-year-old won Olympic gold on 800 meters freestyle.
In total, she has won nine Olympic Games gold medals.
"Better than the Olympic Games"
Australian Kaylee McKeown took the gold on 100 meters backstroke, defeated world record holder Regan Smith, USA, and was also close to snatching the record.
The winning time 57.16 was only three hundredths of a second over Smith's record.
Romanian 21-year-old Olympic gold medalist David Popovici also took home his second World Championship gold on 200 meters freestyle when he sprinted down American Luke Hobson and won with a 31 hundredths margin on 1.43.53.
This was better than the Olympic Games. Before Paris, I trained very hard, but this year I have taken it easy, he says.
