Cosatu spokesperson Sizwe Pamla said the central message of the strike was to highlight the fight against job losses in the public and private sectors.
Pamla said thousands of workers were expected to go on strike.
"Even if workers don't take part, any worker who decides not to go to work tomorrow is protected by the [strike] certificate issued by Nedlac [the National Economic Development and Labour Council]," said Pamla.
Nedlac issues certificates enabling unions to go on strikes.
The SA Democratic Teachers' Union (Sadtu) said its members were joining the strike to voice their concern about the safety of teachers and pupils at schools being targeted by criminals.
"We will use the march to call for increased safety measures in our schools and to urge communities as well as the government to protect them," the union said.
Several other unions have voiced support for the strike, including the National Education Health and Allied Workers' Union (Nehawu), Police and Prisons Civil Rights Union (Popcru), National Union of Mineworkers (NUM) and the SA Commercial Catering and Allied Workers' Union (Saccawu).