Workers are demanding increased social spending and more protections for their rights.
Activities were planned in various parts of the country with the majority of workers encouraged to support the industrial action from home.
The National Union of Metalworkers of South Africa, an affiliate of the South African Federation of Trade Unions (Saftu), gathered near their offices on Eloff Street as they prepared to make their way to Chris Hani Baragwanath Hospital in Soweto via various modes of transport.
The striking workers were also expected to picket outside the the Johannesburg Central Police Station at 12.30pm to support the South African Policing Union (Sapu), whose president Mpho Kwinika was recently fired.
The strike is meant to coincide with the anticipated Budget Speech to be delivered by Finance Minister Tito Mboweni, with left organisations calling for tax hikes aimed at the wealthy, while industry leaders have been calling for tax breaks and relief from the fiscus.
The Saftu national strike is a protected strike under Section 77, meaning every worker regardless of union affiliation had the right to go on strike, according to Numsa.
Workers from ArcelorMittal were expected to picket in Vanderbijlpark, while another picket was planned for New Brighton in Nelson Mandela Bay.
Numsa members in the Western Cape were expected to assemble at Keizersgracht in Cape Town at 11am to begin a convoy to the Parliament buildings.