The casino and original hotel was consented in 1992.
Meanwhile, in a separate deal, SkyCity announced last month that a new hotel would be built on the ex-TVNZ site it bought, rather than a convention centre, which will now be built alongside.
But a spokeswoman defended this, saying the hotel was always planned but not previously announced.
"SkyCity owns a block of land on which it has always envisaged building a convention centre and a hotel," she said.
"During master planning, it was determined that the most rational use of the available land was a regular shaped building for the New Zealand International Convention Centre with an adjacent hotel.
"The Crown accepted this concept design as a better outcome than the options that were being considered in the pre-concept phase.
"The design decision provides a superior outcome for Auckland."