The National Glass Centre will close at the end of July 2026, Sunderland University has announced.
The glass-making and cultural venue, which faced a multimillion-pound repair bill, has been marked for closure since 2023.
It comes after campaigners wrote to the Culture Secretary Lisa Nandy with a renewed plea to save the "world-class cultural asset".
The government said decisions about the building's future were up to its owner.
The building and land is owned by the University of Sunderland, which has been the centre's custodian since 2010.
A spokesperson said no individual or organisation had come forward to offer any financial support towards refurbishing the building.
They added it would cost a minimum £14m, and more likely nearer £45m, to complete the required work "based on independent advice".
"Without that guaranteed level of capital investment, the building does not have a long-term future," a statement said.
"The building will close to the public at the end of July 2026."
The Save the National Glass Centre campaign group sent a letter to the culture secretary earlier this week.
Campaigners called for an "immediate stop" to demolition and relocation plans.
They want an independent review to consider alternatives and a chance to offer their own solutions.
The closure would "end 1,350 years of glass making in Sunderland", the letter added.