Kipketer blasted through the first 200 in 23.47sec and clocked 49.68 for the first lap, but although his victory was never in doubt he could not threaten the record of 1:41.73 which he shares with Britain's Sebastian Coe.
The record, the oldest standing mark in the sport, was set by Coe in 1981. Kipketer equalled the time last month in Stockholm. "I wasn't worried about a record," Kipketer said. "I ran a race where I knew they couldn't catch me."
The 26-year-old, who also smashed the indoor 800m mark twice in three days at the European Championships at Paris in March, has been undefeated in the 800m over the last two years and is the only runner since 1984 to go under 1:42.
Cuba's Norberto Tellez took the silver in 1:44.00 with American Rich Kenah running a lifetime best of 1:44.25 to take the bronze. The Norwegian Olympic champion Vebjoern Rodal was never in contention and finished fifth.
The Kenyan-born Kipketer missed out on the Atlanta Olympics last year because of a wrangle between the Kenyan federation and his adopted Denmark after he renounced his Kenyan citizenship.
Meanwhile, in the women's events, Morocco's Nezha Bidouane recorded one of the biggest shocks of the World Championships with a dramatic late run to win the women's 400m hurdles final.
After hitting the home straight several strides behind the Olympic champion Deon Hemmings and defending champion Kim Batten, the Moroccan produced a remarkable last 100 metres and pipped Hemmings on the line with a final burst after the last hurdle.
Bidouane, who has never done anything of significance at a major championship before, finished in 52.97sec with Hemmings second in 53.09. World record holder Batten hung on for bronze in 53.52.
Bidouane is the second Moroccan gold medallist of the championships. Hicham El Guerrouj, who won the men's 1500m on Wednesday, joined Bidouane on her on her victory lap and helped hoist her into the air.
Bidouane first made her mark in 1990 by winning the African championship, but was unable to go further than the semi-finals at the 1991 World Championships and 1992 Barcelona Olympics. She went out in the heats in the 1993 championships in Stuttgart.Reuse content