The 18-year-old clocked 14 min 19.55sec to smash fellow Australian Kieren Perkins' previous record of 14:26.52 set in 1993 in Auckland, New Zealand.
"I knew I could beat the world record one day but never did I think I could take seven seconds off a record held by Perkins," Hackett said.
Hackett was on course to smash Perkins' record from the outset of the race at the Challenge Stadium in the West Australian capital of Perth.
He was more than two seconds under record pace at the 500m mark and more than four seconds ahead when he turned at the 1 000m mark.
"This was one of the greatest performances in the history of swimming," said a Swim- ming Australia spokesman, Ian Hanson. "The crowd got behind him and gave him a standing ovation for the last 500m of the race - it was incredible."
Hackett is the reigning world champion for 1,500m at both long-course (50m pool) and short-course (25m pool), but has always lived in the shadow of Perkins.
Hackett won the long-course world title in Perth in January when Perkins failed to make the Australian team, before easily beating him to win the gold at this month's Commonwealth Games in Kuala Lumpur.Reuse content