SkyCity will consult on a proposal to slash 700 casual, part-time and full-time rostered staff from its books.
It follows last month's announcement of 200 staff redundancies as part of cost-cutting.
The company said the business needed to be sustainable in the medium and long-term to support the thousands of other jobs that would remain.
The company owns casinos, hotels, bars and restaurants in Auckland, Hamilton, Queenstown and Adelaide.
Unite Union national secretary Gerard Hehir said it was devastating, but just the start of massive redundancies across the entire hospitality sector.