As many as 164 companies will be affected
Thousand of Members of the Southern African Clothing and Textile Workers Union (SACTWU) are set to down tools after talks stalled with footwear manufacturers over wage increases.
SACTWU wants a 10 percent rise in wages but employers are offering 7.75 percent.
"The strike notice was issued yesterday and the strike is due to commence on Monday morning," SACTWU said in a statement.
SACTWU is joining a strike by another larger union in the footwear industry, which began on Monday. Around 164 companies will be affected by the strikes.
Some of the firms supply international footwear giants like Puma and Adidas, SACTWU bargaining officer Vilna Membenkosi said.
The union also declared a wage dispute in the wool and mohair textiles sector, saying employers were offering a 6.5 percent raise against worker demands 9.5 percent.
The dispute had been referred to the industry's bargaining council, it said.
South Africa is nearing the beginning of its mid-year "strike season", in which unions negotiate with employers and sometimes strike when talks go sour.
Members of the Association of Mineworkers and Construction Union downed tools in January at Anglo American Platinum , Impala Platinum, and Lonmin in a strike that has heavily affected economic output in Africa's most advanced economy.
The president of the main platinum union rejected a government-brokered wage offer on Thursday, dashing hopes of an immediate end to a strike that has cut global platinum output by 40 percent.
Meanwhile, South Africa's biggest union said a wage strike in the metals and engineering section was "inevitable" from July, piling more pressure on the sliding economy.
A South African labour court said on Friday a temporary injunction preventing a strike in the gold mining sector by AMCU remained in placed.