The Wollongong star has one of the most illustrious resumes in Australian swimming history but until now there was one item missing from the trophy cabinet.

An individual Olympic gold medal.

That box has now been ticked, McKeon finishing first in a time of 51.96 ahead of Siobhan Haughey, with Cate Campbell in third.

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"I can't believe it," McKeon told Channel 7. "Honestly it doesn't feel real, just the emotions bubbling up."

McKeon qualified fastest for the final, having set an Olympic record in the heat before cruising through semi-final to secure lane four for the medal race.

With the pressure on, the 27-year-old delivered to become just the fourth Australian woman to win the blue-ribbon at an Olympic Games.

It was also the first time since 1956 Australia has had two female athletes on the podium in the event, while McKeon is now the oldest person to take women's 100m freestyle final.

The medal is McKeon's fourth of these Olympics as she continues her quest for seven in Tokyo. It's her second gold, winning the 4x100m freestyle relay, along with bronze in the 100m butterfly and 4x200m freestyle relay.

With four from Rio, McKeon's eight medals leave her one short of Ian Thorpe and Leisel Jone's Australian record of nine.

She will have another three chances to medal, in the 50m freestyle, 4x100 medley relay and 4x100 mixed medley relay.

The relay medals are great, but McKeon said individual glory was a major hurdle to overcome.

"Since that year off from COVID, even the year leading into 2020, I had a big change in my mindset. I worked a lot with my psychologist and honestly my coach (Michael Bohl) is the biggest thing.

"He's coached some incredible athletes, for him to have belief in me that he has, I would be stupid not to have the same belief."

For Campbell, the bronze goes a long way to make up for the disappointment of Rio five years ago.

The Queenslander entered that competition as heavy favourite, only to finish sixth. She is in a different stage of her career and a third-place finish is a significant achievement.

"This is my fourth Olympics and this is only my second individual medal," an emotional Campbell said. "It honestly means the world to me, I'm so happy for Emma, seeing her get up.

"I'm so glad there's going to be an Aus national anthem going through this stadium and I'm so glad that I get to be on the podium and share that moment with her."

The McKeon family had originally planned a week-long party throughout the Games at their Wollongong home, however the COVID lockdown put an end to those plans.

That didn't stop parents Ron and Susie from celebrating the gold medal, with Susie telling Channel 7 their daughter thoroughly deserved the victory.

"She's just got a beautiful soul," Susie said. "She's very reserved, which most people probably wouldn't realise, she just goes about her business and works extremely hard.

"When she came home from Rio everything's been heading towards this moment and wanting that elusive gold medal in an individual event that she hasn't been able to get before.

"Like everyone, it's been a long five years leading towards this with very little time out of the water. She amazes us, she's extraordinary."

Meanwhile NSW MP for Keira Ryan Park has started a push for McKeon to receive a homecoming parade and the keys to the city once Wollongong is out of lockdown.

"You bloody bewdy (sic) Emma McKeon!," Park said in a statement.

"Emma McKeon has given our region the boost it needs right now.

"Emma did more than just become an Olympic champion and set a new Olympic record.

"As our community struggles with the ongoing impact of COVID she has allowed all of us for 51.96 secs to think of nothing else other than cheering her on.

"Her victory is a testament to years of hard work and sacrifice.

"When we are out of this lockdown let's give Emma the homecoming parade she deserves and the keys to the City of Wollongong!"