The court ruled unanimously in favour of Thembekile Mankayi against AngloGold Ashanti.
"This judgment opens the way for compensation claims for occupational health diseases for ex-mineworkers in South Africa," Mankayi's attorney Richard Spoor said in a statement.
The mining companies had been dreading the interpretation and judgment handed down by the court.
"This is a huge step toward the rights and dignity of mine workers being respected and protected by the state.
"What an incredibly important win for mine workers," he said.
Unfortunately, Mankayi died last Friday, "so the judgement comes a week to late for him".
He would be buried in Mthatha on Sunday.