Police are yet to confirm whether the remains are those of the 14-year-old, who disappeared on April 30, but they've informed her family of the discovery.
Northern District Commander Kate Chambers said a crime scene had been declared where the remains were found in bushland near Nabowla, north-east of Launceston.
"It is with a heavy heart that I can confirm that remains were located late this afternoon during our extensive search. While these have not yet been forensically confirmed, they are believed to be human remains," Chambers said.
"We have been in regular contact with Shyanne-Lee's family throughout the investigative process, and have notified them about this latest development.
"Our thoughts continue to be with them and Shyanne-Lee's loved ones during this difficult time."
About 180 police and search and rescue personnel were on Wednesday involved in searches in two locations, including one where a cadaver dog was used.
The bushland search near Nabowla covered more than 50 square kilometres and involved helicopters, motorbikes, ATVs, drones, and horse riders.
It's the largest search operation ever seen in northern Tasmania and the Australian Federal Police has also provided ground-penetrating radar resources.
"Police are following a specific line of inquiry, however no charges have been laid at this stage," Chambers said on Wednesday night.
"Today's search involved 180 people, including police search and rescue specialists, helicopter resources, mounted search and rescue volunteers, State Emergency Service volunteers, and more than 100 Tasmania Police recruits.
"Their support and assistance has been invaluable."
Shyanne-Lee was last seen near Henry Street, in Launceston, near the North Esk River, at about 8.30pm on Sunday, April 30.
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