It is the 10th world record set at the championships in the past three nights.
Germany won silver in 7:53.82, while France (7:55.96) touched out the Australian team (7:56.42) of Libby Lenton, Jodie Henry, Lara Davenport and Stephanie Rice for bronze.
Coughlin swept past Lenton to dictate the race in the opening leg and clocked 1:56.43 to be followed by Dana Vollmer (1:57.49), Lacey Nymeyer (1:59.19) and Katie Hoff (1:56.98).
"I had no idea how well I was doing. I couldn't see anybody. I couldn't tell if I was going fast or not, but I felt strong," Coughlin said.
Tayliah Zimmer had earlier collected another medal for the host nation, winning the bronze in the women's 50m backstroke final.
Zimmer posted a personal best of 28.50, finishing behind American Leila Vaziri (28.16) and Aliaksandra Herasimenia (28.46) of the Belarus.
In other events, Brenton Rickard could add to his medal tally on Friday after qualifying equal-second fastest for the men's 200m breaststroke final.
Rickard, who claimed bronze in the 100m final earlier in the program, dead-heated in his semi-final alongside Italian Paolo Bossini in 2:11.41.
Japan's Olympic champion Kosuke Kitajima led qualifying in 2:10.30. SOURCE: Ã‚Â© 2007 Australian Broadcasting Corporation