Unite union says the pressure is on SkyCity to follow fast food companies and end its zero hour contracts.
The union is due to start negotiations with SkyCity over the contracts at its convention centre.
Zero hour contracts require workers to be on-call but with no guaranteed work.
However, SkyCity said mostly catering staff were on the contracts to give flexibility at trading peaks and for leave coverage.
Unite Union's national director Mike Treen said staff needed security around what hours they worked.
''We're hoping to get guaranteed hours for workers and for that to be able to increase over time.
"Not just a minimum that they must meet, but a guarantee of a certain number of hours each week that they will increase over time."