The members have ties to Iran and Lebanon's "Hezbollah", which is also backed by Tehran.
The Interior Ministry said the 12 had been captured in different areas across Kuwait.
However, the supreme court last month overturned the acquittals of 16 of the accused, and sentenced one of them to life, another to 15 years, and the rest to 10 years each.
Kuwait's Interior Ministry says 12 men with links to a terrorist group associated with Hezbollah and Iran's Revolutionary Guard have been arrested.
Authorities are still searching for two others convicted in the same case and still on the run, the statement added.
The apex court ruling said they were planning attacks across the Gulf state.
Kuwait has protested to Lebanon over the alleged training of the so-called "Abdali Cell" by Hezbollah, which has ministers in the Beirut government.
Iran denies these allegations.
Kuwait had charged 25 of its nationals - all of them Shi'ites - and an Iranian citizen after the discovery of guns and explosives in a raid on the so-called "Abdali cell" in 2015, which escalated sectarian tensions.
"Hezbollah did not form cells in Kuwait and it does not have any cells or members there", he said during his recent televised appearance.