The decision, which comes as a result of prolonged slump in thermal coal prices, is expected to affect 230 employees who are covered by employee agreements, while the remaining jobs are support roles.
Consultation has started with Mount Arthur employees and their representatives with regard to the implementation of the job cuts.
NSW Energy Coal Asset president James Palmer said that the latest decision will enable Mt Arthur Coal mine to be commercially viable, and also provide ongoing employment opportunities in the Hunter Valley.
Palmer added: "Despite extensive work over the past two years to reset our production costs and safely improve the mine’s productivity, Mt Arthur Coal must continue to significantly improve performance to be a globally competitive operation.
"This decision was not taken lightly because we understand it will have a range of impacts on our workforce, their families and the local community. However, the changes will put Mt Arthur Coal on a more sustainable footing for the future."
The company is also planning to axe about 500 jobs at its Drayton mine by the end of 2016 due to difficulty in securing development approvals, reported Sydney Morning Herald?.