The woman threatened a firearms and explosives attack of "a magnitude surpassing the March 15, 2019 Christchurch mosque massacres", causing "significant disruption" to the people of New Zealand.
Otago Polytechnic and University of Otago ceremonies scheduled for December 9 were called off, affecting thousands of graduands.
She stood with her head bowed and hands clasped together in the dock at Auckland District Court this afternoon.
Judge Ema Aitken acknowledged her guilty plea.
"It takes a lot of courage to take responsibility for your actions," she said.
The woman, in her early 20s, will be sentenced on October 28.
She is seeking discharge without conviction.
Her interim name suppression continues until sentencing.
She has been released on existing bail conditions.
The university's Acting Vice-Chancellor Prof Helen Nicholson said she was relieved to learn of the guilty plea.
She wanted to thank the police for their "support and tireless efforts in achieving a result".
"We are extremely grateful to the police for their hard work, expert guidance and support.”
Prof Nicholson also paid tribute to 2020 graduands, their supporters and university staff who, despite the setback of the postponement of eight graduation ceremonies, rallied to celebrate in a less formal way.
