The world number two beat China's defending champion Chen Long 21-15, 21-12, taking control early and never loosening his grip in a relentless performance.

"I still have to take this all in," said Axelsen, 27, who didn't lose a single game in Tokyo.

"This is the biggest achievement you can have as a badminton player and this means the world to me."

Axelsen, who won bronze at the 2016 Rio Games, followed in the footsteps of compatriot Poul-Erik Hoyer-Larsen, the Atlanta Games champion and the last winner from outside Asia.

Hoyer-Larsen, now world badminton's president, was in the arena to watch Axelsen match his achievement.

World number six Chen was bidding to emulate legendary Chinese player Lin Dan in retaining his Olympic title.

But Axelsen held his nerve with the prize in sight, then broke into disbelieving sobs when Chen hit the final shot long.

"When you win an Olympic final in straight games like this against Cheng Long, I think you can say that you've been at least really, really close to your best," added Axelsen, who can speak Chinese.

World number one Kento Momota had exited the competition in the group stage, opening the way for the Dane.

Indonesia's Anthony Sinisuka Ginting took bronze, beating gutsy Guatemalan world number 59 Kevin Cordon 21-11, 21-13.

Ginting's win gave Indonesia two medals on the final day of badminton, after Greysia Polii and Apriyani Rahayu claimed gold in the women's doubles.

It was Indonesia's first Olympic title in women's doubles, and the country's first gold medal of the Tokyo Games.