Simmonds, 17, who powered home on her strong front crawl phase to take a somewhat comfortable win, said that she is "so happy" with her successful evening.
"I'm so pleased with another world record," she said. "I'm just so happy to get on the podium again with another personal best and another world record.
"That was a tough race. I was trying to go as fast as I could and to do another PB I'm just really happy.
"I was really focused on my own swim. You get in your own mindset, you don't really listen to the crowd, but they were great before the race."
Simmonds also won gold in the 400m discipline of the event.