The suspect, Guan, 44, had spiked cartons of herbal tea with poison in Guangdong Province, a Dongguan City police spokesperson said.
Guan was later arrested from a factory dorm.
He told to police that his actions were a way of "taking revenge on society".
Four people are currently in intensive care after drinking the contaminated tea. One died despite medical efforts, according to the spokesperson.
Among those hospitalized, two complained of dizziness, nausea and involuntary spasms yesterday afternoon.
Stores will remove the herbal tea from their shelves, state-run Xinhua news agency reported.