MPs finally voted to oust Yoon Suk Yeol on their second attempt, after the leader's disastrous decree that only lasted six hours on 3 December.
Martial law was declared by President Yoon in a shock television address at 11pm on 3 December local time.
He told South Koreans he needed to free the country from North Korean forces trying to "paralyse the essential functions of the state".
He said: "I declare martial law to protect the free Republic of Korea from the threat of North Korean communist forces, to eradicate the despicable pro-North Korean anti-state forces that are plundering the freedom and happiness of our people, and to protect the free constitutional order."
Analysts described Yoon's decision as a "last ditch attempt" by a "lame duck president" to push his agenda through.
His decision led to chaos, as Seoul residents turned up to the parliament and protested - forming a human shield against heavily armed troops as they tried to seize the parliament.
The leader made a dramatic U-turn just six hours after, as members of his own party slammed his decision, but he survived an immediate impeachment vote.
Lawmakers successfully voted on Saturday, in a second attempt, to remove Yoon from office after his spectacular martial law U-turn last week.
204 out of 300 cast their votes to remove the leader on allegations of insurrection, while 85 voted against.