The 28-year-old completed his successful attempt on the back side of Rist Canyon in Colorado, ascending the 1.93km climb (and riding back down again) 42 times.
Each ascent took an average of around nine minutes, an amazing feat with the attempt done at a starting altitude of 2,200m.
His Strava record for the attempt shows only 8,523m ascenscion due to a lag, but his attempt has been confirmed independently.
Broken several times in recent months, MTB pro rider Keegan Swenson held the latest Everesting record with a time of seven hours, 40 minutes and five seconds before Morton's successful bid.
Morton's attempt drew congratulations from Swenson, and a challenge.
"Lachlan Morton just raised the Everesting bar," the American posted to his Instagram stories, quoting Jonathan Vaughters' post of congratulations. "And he did it at altitude as it should be done.
"Maybe we'll need to have a head to head Everest race."
Before Swenson, former pro roadie Phil Gaimon held the record but Bora-hansgrohe pro Emanuel Buchmann's attempt of seven hours and 28 minutes was deemed unsuccessful by the keepers of the Everesting record Hells 500 because he did not complete repeats of the same climb and his quoted time of seven hours and 28 minutes was moving not elapsed time (which was 7:51:42).
It's Morton's second record ride in just over two weeks. At the end of May, he completed the 225km Kokopelli Trail from Moab, Utah to Loma, Colorado in 11 hours, 14 minutes