Mathis has lived in the estate in the Hollywood Hills since 1959. He says the fire destroyed irreplaceable memories from his career.
“I've got a lot of memories in there. A concert grand piano, all sorts of portraits from my album covers,” he said.
The singer returned from a concert in Cleveland to find his hilltop mansion devastated by fire.
His neighbor Martin Davis told INSIDE EDITION: "The flames were glowing orange and really shooting up high."
The cause of the fire is under investigation. In the meantime, the 80-year-old singer is trying to remain positive.
“I am okay and nobody got hurt. We can always replace things,” he said.