Porte finished third overall on the stage, successfully closing the 99-second gap between himself and Miguel Angel Lopez (Astana Pro Team) and jumping from fourth to third in the GC classification as a result.
The time trial also saw 21-year-old Tadej Pogačar (UAE Team Emirates) produce the ride of his life to snatch the yellow jersey from Primož Roglič (Team Jumbo-Visma) at the final hurdle to cap off an incredible Tour de France debut campaign.
Porte admitted the gravity of his accomplishment had not yet sunk in after the stage but could already envision the overwhelming joy of stepping on to the podium in Paris after the finish on the Champs-Élysées in tomorrow's Stage 21.
"Not really, to be honest, it's absolutely mad," Porte said. "It's been a long day, it'll be a long transfer, so hopefully by the end of this it'll sink in. But it's just a dream that's come true and everyone in the team's played their little part. I just look forward to getting there tomorrow to Paris and getting the race over and done with."
"Taking that step on the podium, it's going to be one of the best days of my life."
The Tasmanian re-emphasised his jubilation of being able to achieve such an honour in a competition he loved losing sleep to tune in for as a child in Australia.
"I mean, when you grow up watching the Tour as a kid in Australia at all sorts of hours, to finally come away with a podium position, it's everyone's dream to be honest," Porte said. "It's just unbelievable."
Porte also expressed his immense gratitude to his fans back home in Australia who have stayed up to witness his amazing efforts in this year's Tour.
"Thanks for staying up, I do appreciate the support," Porte said. "You know, there's a lot of people who've got not such nice things to say about you but there's just so many people that believe in you and that really means the world to me.
"It's been a long journey for me with the Tour, we've had some bad luck, some dramas, but to finally get on to the podium is just the most incredible feeling."
Don't miss out on the Porte podium party and Caleb Ewan contesting the sprint victory on the Champs-Élysées, the final stage of the 2020 Tour de France. Watch on SBS HD and SBS On Demand from 11:30pm AEST and the SBS ŠKODA Tour Tracker from 11:35pm AEST.