Yoon is accused of leading an uprising when he declared martial law over a year ago.
A verdict is expected in February.
The declaration of martial law in December 2024 plunged South Korea into a political crisis. Yoon was ousted a few months later, in April last year, when the country's Constitutional Court ruled that the declaration did not meet the legal requirements for a national emergency.
Yoon is on trial in three additional cases, all linked to the declaration of martial law.
