Miura, who is also an extreme skier, reached the summit of the 29,028-foot Himalayan peak in Nepal about 9 a.m. Thursday, Mainichi Shimbun reported, quoting his Tokyo office.
"It's the greatest feeling in the world. I feel like there's nothing better in life. Even at 80 I can go on and on," Miura said via satellite phone. "I'm practically the most tired I could be. I can see the scenery of the Himalayas before my eyes. It's very beautiful. I've made it here, living up to my efforts and the support I've received."
Miura had previously climbed Everest when he was 70 years old and again when he was 75, Nepalnews.Com reported.
The previous age record was held by Nepal's Min Bahadur Sherchan, who was 76 when he climbed Everest in 2008. Miura's record, however, could be challenged by Sherchen, now 81, who is planning another climb of Everest.
Mainichi reported Miura's team set out from their final camp at an altitude of about 27,900 feet early Thursday morning for the final assault.
The report quoted his daughter that her father's feat was all the more exciting as he had broken his pelvis four years ago while skiing in Sapporo. Since last year, he has had two operations to treat arrhythmia, Mainichi Shimbun said.
As a skier, too, Miura's accomplishments are impressive, having raced down the highest mountains on each of the seven continents, the report said.
His father, Keizo, had kept skiing until just prior to his death at age 101.
Miura's motto is, "Rather than a reason why you can't do it; think of a reason why you can do it."