In an early Thursday morning session, South Korea opposition presented the impeachment motion to parliament.
“This is an unforgivable crime — one that cannot, should not, and will not be pardoned,” MP Kim Seung-won said.
Under South Korean law, the motion must be voted on between 24 and 72 hours after it is presented to a parliamentary session, according to Yonhap news agency.
The main South Korea opposition opposition Democratic Party has also filed a complaint of “insurrection” against the president, some of his ministers and top military and police officials — which can carry a penalty of life imprisonment or even death.
In a show of public anger with Yoon, thousands of protesters converged around his office in central Seoul late Wednesday after staging a rally in Gwanghwamun Square, demanding his resignation.
Seoul’s stock exchange closed down more than one percent Wednesday as markets were roiled by the turmoil.
Even the leader of Yoon’s own ruling party described the martial law attempt as “tragic” while calling for those involved to be held accountable.
But party lawmakers then decided to oppose the motion to impeach Yoon, Yonhap reported early Thursday.
Lawmakers defiant
In his late-night television announcement imposing martial law on Tuesday, Yoon cited the threat of North Korea and “anti-state forces”.
More than 280 troops, some flown in by helicopters, arrived at parliament to lock down the site.
But 190 lawmakers defied rifle-carrying soldiers to force their way into the building to vote against the move.
The constitution says martial law must be lifted when a parliamentary majority demands it, leaving Yoon with little choice but to retract his decision and call off the military in another televised address six hours later.
Senior aides to Yoon offered to resign en masse Wednesday, as did the defence minister, who took “full responsibility for the confusion and concern” around the martial law declaration.
By evening, Yoon had yet to publicly reappear.
The repeal of martial law prompted jubilation among flag-waving protesters outside parliament who had braved freezing temperatures to keep vigil through the night in defiance of Yoon’s order.