Chris Picco took a guitar into the neo-natal ward to sing "Blackbird" to his son Lennon, born prematurely by emergency Caesarian section last weekend.
The boy was born at 24 weeks on November 8, but his mother Ashley died the same day.
The infant survived three days in the neo-natal ward at Loma Linda University Hospital outside Los Angeles and died on November 11.
A video of the baby's father playing the song by his incubator had been watched over half a million times Thursday with tens of thousands more views every few minutes.
The heartbreaking video of baby Lennon singing 'Blackbird' to comfort dying baby son after wife died in childbirth goes viral - Source YouTube
"Our dear Ashley’s life was tragically, devastatingly cut short this past weekend. Her dear baby flickered briefly for a few days after," said a statement on a memorial website.
A family spokesman, Brett Walls, told AFP: "For the next few days, Chris is spending time with his family, his friends, and his community while he continues to grieve.
"He recognizes the chord this is striking with people and would be interested in seeing how we could partner to bring healing to others who are suffering," he said in an email.