Mr Kiernan is best know for the BBC shows, Still Game
and Chewin' The Fat
The 12-year-old son of Scottish comedian and actor Ford Kiernan has been found dead at the family home in the west end of Glasgow.
Police Scotland said they received a report of the child's death late on Monday night.
Sonny was the younger of 51-year-old Mr Kiernan's two children and his death is currently being treated as unexplained.
A post mortem examination will be carried out in due course to establish the exact cause of death.
A Police Scotland spokeswoman said: "Around 11.30pm on Monday January 6, police received a report of the death of a 12-year-old boy in Glasgow.
"A post-mortem will be carried out in due course to establish the exact cause of death.
"The death is currently being treated as unexplained and inquiries are continuing."
Mr Kiernan lives with his wife Lesley and their other child.
He and his comedy partner Greg Hemphill are best known for the popular BBC Scotland shows Still Game and Chewin' The Fat.
They are due to revive their characters Jack Jarvis and Victor McDade for a run of live stage shows of Still Game at The SSE Hydro in Glasgow this autumn.
No new episodes of the show have been recorded since a Hogmanay special which was broadcast in January 2008.