The court also fined the unnamed Kuwaiti national, who was a top official at the Kuwait municipality, $30,000 and convicted him of calling other people to join the group.
The ruling is final and cannot be challenged.
Kuwaiti courts have sentenced a number of IS members, sympathisers and financiers to various jail terms.
A lower court in December sentenced a Filipina to 10 years in jail after convicting her of joining the jihadist group and plotting attacks.
Authorities in July said they had dismantled three IS cells plotting attacks, including a suicide bombing against a Shia mosque and against an interior ministry target.
An IS-linked suicide bomber killed 26 worshippers in June 2015 when he blew himself up in a Shia mosque, in the worst such attack in the Gulf state's history.
