James Dunleavy, 40, killed his 66-year old mother Philomena at his flat in Balgreen Road, Edinburgh, after an argument, a court heard.
The High Court in Edinburgh heard the slightly built woman had travelled from Dublin to visit her son, who was also known as Seamus.
He was on trial for murder but a jury accepted his plea to the reduced charge of culpable homicide.
Mrs Dunleavy's remains were found last year on the city's Corstorphine Hill.
Dunleavy was sent to the State Hospital at Carstairs for psychiatric assessment.