Just one woman had previously won seven in any sport, at any Olympics: Russian gymnast Maria Gorokhovskaya in 1952.
McKeon's career total of 11 Olympic medals is now more than any other Australian, eclipsing the nine of Ian Thorpe and Leisel Jones.
"I'm so proud of myself," McKeon said.
"And I wouldn't be able to do it without all the support behind me. It's an honour to do this and I know I've worked hard for it."
Australian swimmers captured nine golds in Tokyo, bettering the nation's previous record of eight at the 1956 Melbourne Games.
And with three silvers and eight bronze, the Tokyo haul of 20 swimming medals equals the nation's benchmark from the 2008 Beijing Games.
McKeon also becomes the first Australian to win four gold at a single Games.
And her three bronze add to her collection from the 2016 Rio Olympics of one gold, two silvers and a bronze.
Backstroker Kaylee McKeown, aged just 20, snared three gold medals after helping McKeon, Hodges and Campbell to a dramatic victory in Sunday's medley final.
After trailing the United States for the initial three laps, Campbell's stunning last freestyle leg delivered victory by just 0.13 seconds.
"All credit to the incredible job the Australians have done this week," Campbell said.
"I am so so proud to be a member of this team.
Meanwhile, Australian two-time world champion Logan Martin has dominated the men's BMX freestyle competition to win the gold medal.
The 27-year-old from Logan Reserve in Queensland was untouchable, posting the top scores throughout the men's runs as his sport made a riveting Olympics debut in Tokyo.
It is also Australian cycling's first Olympic gold medal since Anna Meares won the women's sprint at the London 2012 Games.
Martin was the only competitor to score more than 90 in Saturday's two seeding runs, confirming he was the man to beat.
Sailor Matt Wearn won Australia's fourth gold later on Sunday in the Laser, marking the first time ever Australia has won a quartet of Olympic gold medals on one day.
Wearn's dominance throughout 10 regular races meant he only needed to attempt to finish the final race on Sunday to win gold.
It is Australia's third consecutive Olympic gold medal in the one-man class, with the 25-year-old following in the footsteps of Tom Burton (Rio 2016) and Tom Slingsby (London 2012).