With disruptions expected during rush hour, the Seoul Metropolitan Government said the subway will run for extended hours with additional trains put into service.
The city's 25 districts will also provide 480 shuttle buses to carry commuters to subway stations.
The full scale strike by the city's bus drivers is the first in 12 years. Their last strike lasted for around 20 minutes.
Oh Jeong-hui, a 25-year-old from Seoul, said she left home early after hearing about the strike. "Normally it would take 15 minutes by bus but I took the subway and had to transfer which took around 30 minutes," she said.
The negotiations between the Seoul Bus Labor Union, which represents drivers serving over 97% of bus operations, and their employers failed after the union demand for a 12.7% hike in hourly wages was dismissed as "excessive," Yonhap reported.
"We'll make an all-out effort to smoothly reach an agreement between the union and the management soon," Yoon Jong-jang, a head of the Transportation Planning Bureau at the Seoul Metropolitan Government, said in a statement.
Buses in Seoul are operated on a quasi-public system in which private companies manage the buses while it's heavily subsidised and regulated by Seoul's city government to ensure accessibility of services.
Seoul Mayor Oh Se-hoon pleaded for a swift compromise. "City buses are the legs of the citizens; their livelihood and daily lives literally depend on them," he said.
South Korea also has an ongoing doctors' strike as thousands of trainee doctors have walked off their jobs in protest against the government's plan to increase medical school admissions.
Critics have said the authorities should prioritise improving the working conditions of trainee doctors while the government says the plan is vital to remedy a shortage of doctors in one of the world's fastest-ageing societies.
(Reporting by Hyunsu Yim; Editing by Michael Perry and Miral Fahmy)
By Hyunsu Yim
