Deng Mingjian, 41, was sentenced to three years in jail with a reprieve period of four years for intentional homicide, the Panyu District People's Court ruling said.
Deng purchased two bottles of pesticide on May 16, 2011 at the request of his mother Li Shulan, 73, who suffered from hemiplegia for 20 years, the ruling said.
She died the same day just minutes after drinking the pesticide, state-run Xinhua news agency reported today.
Deng was described as a "filial son" and was said to have taken care of his mother for decades.
Several of his neighbours and relatives asked the court to give him a lenient sentence for this reason.
The court considered Deng's guilty plea and the appeals of the public in making its ruling.