Lyu Yueting, 39, was found guilty of adding "dangerous substances" to food by the Shijiazhuang Municipal Intermediate People's Court in north China.
This resulted in one person becoming seriously ill, left 12 others with minor illnesses, and caused significant financial loss, the Shijiazhuang Municipal People's Procuratorate told state-run Xinhua news agency.
Considering the sensitivities involved in view of China-Japan tensions over the disputed islands, the Shijiazhuang Municipal Intermediate People's Court delivered the verdict in a public hearing with the presence of journalists and officials from the Japanese embassy in Beijing.
Between July and August 2007, Lyu entered the plant's refrigeration storehouse and attempted to inject insecticide into the dumplings with syringes but failed.
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He re-entered the refrigeration storehouse three times between October and December 2007 and injected insecticide into six to nine boxes of frozen dumplings.
The contaminated dumplings were sold to Japan and the Hebei's city of Chengde.
The incident that took place ahead of the Beijing Olympics raised tensions between China and Japan.
Lyu confessed to the crime in court, saying he felt sorry for the people who fell ill and did not expect his acts to cause such a serious consequence.
It was not clear whether Lyu plans to appeal, the report said.
In January 2008, Japanese media reported that 10 people fell ill after consuming frozen meat dumplings produced by the plant.
The Tianyang Food Plant recalled its products and suspended production after the incident, resulting in a loss of over 5.5 million yuan (about USD 9.8 lakhs).
The plant was investigated by both Chinese and Japanese authorities shortly after the incident but no problems were found. In March 2010, Lyu was detained by Chinese police.