Coun Maxine Callow questioned whether the state-of-the-art facilities at the Winter Gardens would fulfill their potential now many gatherings were still being held online.
She told a meeting of the council's Audit Committee: "I do agree at the beginning this was much needed, but with all the delays we now have his conference centre at a time when because of Covid people can hold conferences on Zoom.
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"Will this impact our conference centre? I am worried this could become a white elephant.
"It was something that was essential, but because of timing I wonder if we need this round our neck."
But Alan Cavill, director of communication and regeneration at the council, said the venue was already busy and was set up to host different kinds of events, not just conferences.
These could include online events such as gaming due to the technology fitted in the complex, while the World Matchplay Darts, recently held at the Winter Gardens, had used the conferencing facilities as a VIP area.
Mr Cavill added other destinations were continuing to invest in conference facilities.
He said: "Everywhere around the country that has conference facilities is either investing in them or growing them.
"For example Southport is demolishing its conference centre and building a new one.
"We think we're in a unique position to be able to offer something no-one else can offer.
"Our venue is new and old, and people want authenticity and something new."
The centre was affected by delays including disputes with the contractor, and cost rises partly due to the complexity of attaching the new structure to the Victorian Winter Gardens.
Building work began in 2018 and originally it had been hoped to open the facility in spring 2020, but the Covid pandemic and lockdowns led to further hold ups.
The conference centre finally opened in spring this year with the first major event being the Conservative Party Spring Conference.
Shopworkers union USDAW also held its conference at the centre in May, bringing about 850 delegates to Blackpool.