Chandulal-Mackay said he raised the issue with elected members and council staff last year and he was pleased to see it had quickly progressed to the decision-making stage.
Consultation has already been done with Friends of the Opera House, the group of dedicated volunteers who devote themselves to the preservation of New Zealand's only Victorian-style theatre.
Although not unanimously in favour of the name change, 74 per cent said they would support altering the name. Another 13 per cent said they were not in support and 8 per cent were neutral, noting they would be happy either way.
Chandulal-Mackay said altering the name would provide consistency with other council venues and there had been confusion expressed by promoters and visitors as well as questions about why the spelling had not been updated.
"Whanganui has been the official spelling of our district since 2015 and it no longer makes sense to have an iconic cultural emblem like the Opera House using the incorrect spelling," he said.
"If the committee votes to support this change next week then it will move to the full council for final approval."
First named the Municipal Opera House, the building designed by Wellington architect George C Stevenson was constructed by Whanganui contractor George Meuli in 1899.
Permission from Buckingham Palace was granted to add the word "Royal" to the name for the centenary year in 2000.