Lieutenant Colonel Yuan Hsiao-feng was convicted on 12 accounts of leaking confidential military information to China between 2003 and 2007, the supreme court said.
Yuan handed the secrets to China via retired colleague Chen Wen-jen, who was recruited by Beijing after he went there to do business. Chen received a 20-year jail term for his involvement in the case, according to the court.
The court also imposed a fine of USD 260,000 on Yuan - the amount of payment he collected for passing the secrets. The ruling is final.
Taiwan and China have spied on each other ever since they split in 1949 at the end of a civil war. Beijing still regards the self-ruled island as part of its territory awaiting reunification, by force if necessary.
Also Read
Taiwan has been rocked by a spate of espionage scandals in recent years, reflecting the fact that intelligence gathering has continued despite warming ties with China under current Taiwanese President Ma Ying-jeou.
In September 2013, a retired vice admiral was jailed for 14 months for collecting confidential military information for China, just months after an ex-lieutenant general was indicted for leaking secrets to Beijing.