SEOUL—South Korea’s parliament voted to end martial law, coming just hours after the country’s president declared the move due to opposition parties that had made the nation vulnerable to North Korean “communist forces.”

The early Wednesday morning vote was 190 to 0, as lawmakers scaled fences and encountered armed guards as they entered the country’s National Assembly building in downtown Seoul. Martial law had been declared more than two hours earlier, taking effect at 11 p.m. local time on Tuesday.