Employees at Anglo America Platinum, Impala Platinum and Lonmin will have to undergo medical checks and safety training before they begin work again.
The firms said it would be “some time” before they resumed full production.
The “safety and wellness of employees was paramount”, the companies said.
The firms estimate the strike has so far cost them more than 24bn rand ($2.3bn; £1.3bn) while employees have lost about 10.6bn rand in wages.
“It is our sincere hope that our companies, our industry, our employees and all other stakeholders will never again have to endure the pain and suffering of this unprecedented strike period. None of us, nor the country as a whole, can afford a repetition,” the chief executives of the three mining firms said in a joint statement.