The 31-year-old Leeds star yesterday confirmed that he would be attempting to repeat the stunning successes he enjoyed at both London 2012 and Rio 2016.
He had refused to commit either way over the last three-and-a-half years but has now made his mind up in favour of another tilt at gold.
In an interview with the BBC, Brownlee said an injury-free year had helped convince him to try and secure a hat-trick of Olympic titles in Tokyo this summer.
“A year ago I wouldn’t be doing this because I knew I couldn’t cope with another bad injury,” explained Brownlee.
“I just wanted to be able to run and compete and enjoy it.
“But in the past year I haven’t been injured. I’ve really enjoyed training and I’ve really enjoyed competing, and preparing to compete.
“And so the decision crept up on me a bit, really.
“I want to go to another Olympics and I want to see what I might be able to do.”
Brownlee has raced sparingly over the Olympic distance since Rio, and with substantially less success than he had been accustomed to.
His last victory in the elite world series came in his home city of Leeds back in 2017, although he did win a fourth European title last June.
Brownlee’s first task will simply be to qualify for the British team and, should he make it, he insisted that his marker of success extends beyond attempting to return home with a gold medal around his neck once again.
“I’m happy because I want to be racing on the biggest stage and being competitive,” he insisted.
“The 12-year-old me dreamed of going to one Olympics. So to pass up the chance of just seeing where it leads me this year would be a bit mad.
“In my head, the perfect scenario is that I’m in a position where I’m stood on the start-line and I think I can win the race.
“But, if I’m instead thinking I can scrape a third here, or I’m thinking I could help another British athlete win a medal here, I would be happy with that.
“I really would.”
Last year, Brownlee was left contemplating his future in the sport he had dominated for so long after a disappointingly heavy defeat in the ITU World Series event in Leeds.
The two-time winner of the race finished a distant 44th and, in the immediate aftermath of the event, speculated that he might even retire, so injury-riddled he had been in the months leading up to the event.
But those thoughts are long gone, with another reason for him wishing to be in Tokyo is that he is the proposed British candidate for the International Olympic Committee’s Athletes’ Commission.
If the IOC ratifies his candidature, Brownlee would be involved in a secret ballot which would take place in the Japanese capital ahead of the 2020 Games.
Four athletes from four different sports would be elected to the commission, who automatically become IOC members.
The four athletes chosen will serve an eight-year term through to Los Angeles 2028.
The purpose of the Athletes’ Commission is to ensure the competitors’ viewpoint is put forward at IOC level.
Brownlee finished 21st on his debut in the Ironman World Championship in Hawaii in October but has qualified for this autumn’s race after winning Ironman Western Australia before Christmas.