The theatre would seat about 650-700 people, double the capacity of the current largest theatre - Capitaine Bougainville Theatre at Forum North. The convention centre would seat about 500 people.
"We used to be able to get New Zealand's best talent and we haven't been able to recently ... because we don't have the facilities," Mr Halse said.
"We can't attract the musicals and the roadshows so we're missing out on a lot of opportunities."
Where the proposed theatre and conference centre was eventually located could depend on council's consolidation of its current three premises - Forum North, Walton Plaza and the Civic Arcade.
The rationale behind consolidating the council premises had been providing better service to customers and improving productivity and efficiency by eliminating a duplication of functions.
It would also reduce rent as the council did not own Walton Plaza and the Civic Arcade.
The Long Term Plan (LTP) outlined three options for this, though the option being planned for was a $10 million expansion of the current administration facility at Forum North scheduled to be completed around 2018.
Another option, which Mr Halse said he favoured, was leasing space in new private development in the CBD. It would free up Forum North to house the new theatre and conference centre, he said.