The former Good Morning Britain host, 56, believes he caught the virus after crowds of ticketless fans flooded the venue.
Piers received both doses of the AstraZeneca vaccine, but began to show symptoms two days after the game, including a raging fever, chills and violent coughing and sneezing.
He said it was “the hardest thing I have felt” from an illness in his adult life.
Piers said he believed he caught the Delta variant of the coronavirus a fortnight ago in the final, which saw Italy beat the England squad after the penalty shootout.
“My confidence that the event would be ‘covid safe’ had disintegrated,” Piers said. “It was becoming an unregulated free-for-all. “
After starting to experience symptoms, Piers underwent a lateral flow test which came back positive and a PCR test confirmed the result.
He suffered from fever, cold sweats, coughs, sneezes and “strange aches”.
Piers has now recovered from his symptoms, but he says his voice is deep.
He told the Mail on Sunday: “My voice now sounds like Barry White’s, although I couldn’t feel less like a love walrus. “
Piers added, “It is certainly the hardest illness I have felt in my adult life, BUT, as I slowly come out the other side, coughing and spitting. “
“I am still here – unlike so many millions of people around the world who have lost their lives to Covid in this pandemic.
“For this, I owe a sincere debt to the brilliant scientists at Oxford who created the Astra-Zeneca vaccine at such astonishing speed. “
The AstraZeneca vaccine has been shown to be around 70% effective in stopping the transmission of Covid.
It is 60-73% effective in stopping symptoms and 80% effective in stopping serious illness due to Covid.
Piers had shared photos of himself in the crowd watching the game with his sons.
He later shared a video of himself in the stadium with comedian Jack Whitehall.
He was also seen posing for photos with football fans who asked him for a photo.
Officials had assured fans attending the final that only spectators who were fully vaccinated, or those who tested negative, would be allowed into the stadium.
Throughout the pandemic, Piers had been one of the government’s most vocal critics while on Good Morning Britain.
He had criticized ministers for refusing to appear on GMB for 201 days, a race that was ultimately halted when then-Health Secretary Matt Hancock appeared on the show in November.
Earlier this week, Piers denounced people who refuse to be vaccinated, calling them “deceived ignorant morons.”
Piers tweeted: “People have the right not to be vaccinated against covid.
“Just as I have a right to think that they are selfish and deceived ignorant morons who will keep this pandemic going much longer than it should.” “