Kim Dong Chul was arrested in North Korea in October and had admitted to committing "unpardonable espionage" including stealing military secrets, the North's official news agency reported earlier.
"The Supreme Court of the Democratic People's Republic of Korea on Friday sentenced South Korea-born U.S. citizen Kim Dong-chul to 10 years of hard labour for subversion of the DPRK social system and espionage activities," Xinhua said.
There were no further details.
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North Korea, which has been criticized for its poor human rights record for years, has used detained Americans in the past to extract high-profile visits from the United States, with which it has no formal diplomatic relations.
It has previously handed down lengthy sentences to foreigners before eventually freeing them.
Six foreigners, including Kim and three South Koreans, are known to be detained in the North.
Kim, who has said he was a naturalised American citizen, had confessed to committing espionage under the direction of the U.S. and South Korean governments and apologised for his crimes, according to the North's KCNA news agency.
Some foreigners held by North Korea have said after their release that their confessions were coerced.
The North is also holding an American, Otto Warmbier, who was sentenced to 15 years of hard labour in March for trying to steal a propaganda banner. It is also holding a Korean-Canadian Christian pastor, who is serving a life sentence for subversion.
North Korea has tightened security ahead of the first ruling party congress in 36 years which will begin on May 6. It has also intensified its pursuit of nuclear weapons and ballistic missiles since its fourth nuclear test in January.
