US Edition The London-listed miner said it had agreed with unions to cut 4,000 full-time and contract staff, including 300 managers, at its Marikana mine and 1,500 at its Limpopo mine.
Platinum producers have been hard hit by the collapse in the new car market as the metal is used in catalytic converters.
Lonmin chief executive Ian Farmer said: "With the current backdrop of challenging economic conditions, these agreements are an important milestone in our objective of restructuring the Company. At Marikana, we are now focused on engaging with our employees to complete the required downsizing. At Limpopo, the Baobab shaft will be put on care and maintenance as soon as possible.
"Our dialogue with the unions has been constructive and pragmatic. We appreciate their active engagement during this difficult period. Whilst the unions have understandably executed their mandate to protect the interests of their members, they have displayed an appreciation of our efforts to ensure the long term sustainability of the company."
It said full details on the total number of job losses and the costs of the restructuring will be announced at its annual results on Monday May 11.
Last week Anglo American announced plans to axe 19,000 jobs this year and scrapped its final dividend. The company will lose 10pc of its workforce to achieve cost-savings of $2bn (£1.4bn).