The conviction for obstruction of justice and other charges comes on top of a life sentence he has already received on rebellion charges stemming from his baffling authoritarian push, which triggered the most serious crisis for the country's democracy in decades.
Judge Yoon Sung-sik of the Seoul High Court said the conservative former president sidestepped a legally mandated full cabinet meeting before declaring martial law, falsified documents to conceal the lapse, and deployed security officials "like a private army" to resist law enforcement efforts to arrest him in the weeks following his impeachment.
Yoon stood quietly on Wednesday as the verdict was delivered and made no comment.
A lower court in January sentenced Yoon to five years in prison but partially cleared him of abuse-of-power charges tied to the Cabinet meeting ahead of the martial law declaration, finding he was not responsible for the failure to attend of two members who were invited to attend.
The Seoul High Court reversed that acquittal, finding him guilty on all counts and ruling that he violated the rights of those two as well as seven other cabinet members who were not notified by convening only a select few to simulate a formal meeting.
Though brief, Yoon's December 3, 2024, martial law decree threw the country into a severe political crisis, paralysing politics and high-level diplomacy and rattling financial markets.
The turmoil eased only after his liberal rival, Lee Jae-myung, won an early presidential election in June.
Yoon was suspended from office on December 14, 2024 after being impeached by the liberal-led legislature and was formally removed by the Constitutional Court in April 2025.
Following his suspension from office, he refused to comply with a Seoul court's warrant to detain him for questioning, setting up a stand-off in which dozens of investigators arrived at the presidential residence in early January 2025 but were blocked by presidential security forces and vehicle barricades.
He was detained later that month, released by another court in March, and was then re-arrested in July.
He remained in custody after that as a series of criminal trials, which are continuing, began.
