George commenced at Wiener Stadthalle after postponing the tour in November when he fell ill.
"This is one of the greatest honours of my life, to sing to the men and women who saved my life," he said.
Michael getting face to face with crowd expressed them it was "great to be alive", and performed a rendition of Nina Simone's Feeling Good at the request of one of the doctors.
He also performed his new single White Light, inspired by his near-death experience.
"I think given the manner of men and women who did save my life, we could not go without singing this song," he said.