The Toronto-based pastor, who is of South Korean origin, reportedly confessed earlier to a "subversive plot" to overthrow the government and set up a "religious state".
North Korea bans religious activity.
North Korea periodically detains foreigners for religious or missionary activity.
Associated Press and China`s state run Xinhua, which both have a presence in Pyongyang, reported that Lim was given the sentence after a brief trial at the North Korean supreme court.
North Korean state media KCNA has not reported the court`s decision.
`Subversive plots`
Mr Lim and his colleagues travelled to Pyongyang on 31 January as part of a humanitarian mission. His family said it was to support a nursing home, nursery and orphanage.
Mr Lim, who heads the Light Korean Presbyterian Church, had made numerous humanitarian aid missions to North Korea for nearly two decades, the church said.
He was detained in February and in July a KCNA report said Mr Lim gave a press conference in Pyongyang where he admitted to using humanitarian work as a "guise" for "subversive plots and activities in a sinister bid to build a religious state".
He also reportedly admitted to giving lectures that "North Korea should be collapsed with the love of `God`", and helping the US and South Korea to aid North Korean defectors.
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