Donto James, 43, explained the legendary singer - who died Friday at the age of 73 following a battle with leukemia - spent her final moments in his arms, which was a "true gift".
He told People.com: "It's been quite a day but I'm very grateful. She basically passed in my arms, and I was able to share everything I needed to say to her, from praying to listing her accomplishments as a mother.
"I asked her if she heard what I said, and she'd flutter her eyes and look at me very quickly. And she had been nonreactive before that.
"It was spiritual and a true gift to be with her when it happened. I wouldn't want it any other way than for her to go in our arms."
In a tribute to the 'At Last' hitmaker - who was admitted to a hospital in Riverside, California, as her condition deteriorated on Thursday night - Donto praised his mother as a "wonderful" woman.
He said: "I told her that I loved her. I said, 'You were a wonderful mother, you did a wonderful job, your seven grandchildren love you, and they will be okay.'
"For sure, the world lost a legend today. I am very proud of her, and very thankful."
Beyonce Knowles - who portrayed the singer in 2008 movie 'Cadillac Records' - was just one of a whole host of stars paying tribute to the late Etta, admitting she was "fortunate" to have met her.
She said in a statement: "Etta James was one of the greatest vocalists of our time. I am so fortunate to have met such a queen. Her musical contributions will last a lifetime.
"Playing Etta James taught me so much about myself, and singing her music inspired me to be a stronger artist.
"When she effortlessly opened her mouth, you could hear her pain and triumph. Her deeply emotional way of delivering a song told her story with no filter. She was fearless, and had guts. She will be missed."
