He had been admitted to Hilal-i-Ahmer Hospital in Latifabad on Friday following cardiac complaints.
He leaves behind his wife, three sons and a large number of admirers to mourn his death.
His body has been placed in the Agha Khan mortuary which will be buried after the arrival of his three sons who live abroad.
Sindh Taraqqi Pasand Party chairman Dr Qadir Magsi and a number of writers have expressed profound sorrow and grief over the demise of Mr Panwahar.