The Japanese former extreme skier previously climbed the 29,035ft Himalayan peak when he was 70 and 75.
Yesterday, he reached the world’s highest point at 9:05 local time after climbing the south-east ridge route pioneered by Sir Edmund Hillary and sherpa Tenzing Norgay 60 years ago.
Even more remarkably, Mr Miura completed the feat after beginning the year with his fourth heart operation.
His achievement may be short-lived, however. An 81-year-old Nepalese climber aims to scale Everest next week.
Mr Miura’s moment of glory was captured on video from six miles away, using a camera crew at 18,000ft on another peak.
“We have arrived at the summit,” Mr Miura said in a radio transmission from the world’s highest point. “Eighty years and seven months… The world’s most incredible mountaineering team had helped me all the way up here.”
Mr Miura and son Gota made a phone call from the summit, prompting his daughter Emili to smile broadly and clap her hands in footage shown by Japanese public broadcaster NHK.
“I made it!” Mr Miura said over the phone. “I never imagined I could make it to the top of Everest at age 80. This is the world’s best feeling, although I’m totally exhausted. Even at 80, I can still do quite well.”
Nepalese mountaineering official Gyanendra Shrestha, at Everest base camp, confirmed Mr Miura was the oldest person to reach the summit.
The previous oldest was Nepal’s Min Bahadur Sherchan, the octogenarian on Mr Miura’s heels. Mr Sherchan is preparing to scale the peak despite digestive problems he suffered several days ago. On Wednesday, he said by phone from base camp that he was in good health and “ready to take up the challenge.”
The two elderly mountaineers have crossed paths before.
Mr Miura, who had become the oldest Everest climber with his ascent at age 70, would have reclaimed the title in 2008 as a 75-year-old, but Mr Sherchan, then 76, reached the summit just a day before he did.
Emili Miura said her father “doesn’t really care” about the rivalry. “He’s doing it for his own challenge,” she added.
Mr Sherchan’s team leader, Temba said Mr Sherchan will congratulate the new record holder when he returns to base camp, but would not turn back until he completes his mission.
Mr Sherchan got good news yesterday when Nepal’s government approved financial aid for his climb. The cabinet approved $11,200 (£7,400) for his expedition and waived $70,000 in permit fees, said Bimal Gautam, press adviser to the chairman of the Council of Ministers.
Mr Miura underwent heart surgery in January for arrhythmia, his fourth heart operation since 2007, according to his daughter. He also broke his pelvis and left thigh bone in a 2009 skiing accident.
On his expedition’s website, he explained his attempt to scale Everest at an advanced age: “It is to challenge [my] own ultimate limit. It is to honour the great Mother Nature.”
He said a successful climb would raise the bar for Japanese of every age. “This will be deeply touching to all the people of Japan. And, especially, in an ageing society, it will also give much courage and hope to all elderly people,” added Japan’s chief cabinet secretary Yoshihide Suga.
Nearly 4,000 climbers have summited Everest since the pioneering May 1953 climb; 240 have died in the attempt.