The 24-year-old's total of 9,039 points improved on Czech Roman Sebrle's 2001 mark by 13 points, an achievement made more stunning by the rainy and cold conditions over the two days of the decathlon competition.
Eaton's triumph came on the track where he trains and the support he received in the final 1,500 metres leg of the 10-event competition, had made the record so special, he said.
"That is when the crowd really lifted me," he said. "That last 600 metres I was not running with my own legs. It was incredible.
"I don't care what anyone says, there is magic here," the world silver medallist said of the University of Oregon's Hayward Field.
The sense of occasion was heightened by the presence of many of the United States' greatest decathletes, including Dan O'Brien, Bruce Jenner and Rafer Johnson, who were at the trials to celebrate the 100th anniversary of the first Olympic decathlon.
Already the world indoor pentathlon record holder, many had tabbed the Oregon native to be the next holder of the decathlon record.
Eaton, himself, said he expected to become the second man to top 9,000 points in multi-event competition.
The weather provided an obstacle but Eaton won seven of the 10 events for a massive 646-point victory over world champion Trey Hardee, wiping out O'Brien's 1992 national record of 8,891 points in the process.
He had already set the best ever marks in decathlon for the 100 metres and long jump legs on Friday and capped off the competition with a gutsy 1,500 metres.
"I knew the possibilities (of the world record) after the javelin, maybe the pole vault, so I just kind of went with it," he said.
Eaton said there was more to come.
"The great thing about this is, I feel like I have not maximized yet," he said. "I am just getting going.
"I feel like I can still run faster, jump higher ... and clearly I can throw farther."
Bryan Clay's chances of defending his Olympic decathlon title ended on Saturday after a sequence of events, including a temporary disqualification, left him short of the points needed to make the US team.
He was disqualified from the 110 metres hurdles at the national trials after he hit the ninth obstacle, stumbled and pushed it over but he filed a protest and was later reinstated.
It proved immaterial, however, as Clay went on to foul on all three of his discus throws, leaving him with no points in the discipline and no chance of finishing in the top three of the 10-event competition.
Only the top three qualify for the London Olympics next month.
"I am sure it (the protest) weighed on Bryan in the discus," Clay's manager Paul Doyle told Reuters while making clear the decathlete would finish the trials.
"He wants to go out with dignity."