The partial human remains were discovered in Carlton Reserve just hours before the FBI also uncovered a backpack and notebook belonging to Mr Laundrie at Myakkahatchee Creek Environmental Park.
The area where they were found had been under water during earlier searches.
“On October 21, 2021, a comparison of dental records confirmed that the human remains found at the T Mabry Carlton Jr Memorial Reserve and Myakkahatchee Creek Environmental Park are those of Brian Laundrie,” the FBI said in a statement.
A lawyer for his parents, Steve Bertolino, also confirmed they were told the remains were those of their son.
“We have no further comment at this time and we ask that you respect the Laundrie’s privacy at this time,” the statement said.
It comes more than a month after the 23-year-old was reported missing, sparking a large-scale manhunt involving federal, state and local law enforcement.
Person of interest in death of Gabby Petito
He vanished two weeks after returning home alone from a cross-country van trip with his former partner Ms Petito on September 1.
The pair gained an online following after documenting their travels on YouTube until Ms Petitio disappeared without a trace.
It later emerged they were stopped by police in Utah on August 12 after a physical altercation but no domestic violence charges were filed.
The police department there is conducting an internal review to determine if policy was followed.
Mr Laundrie refused to speak with investigators about her disappearance despite not being accused of any wrongdoing.
He was reportedly last seen by his parents on September 14, who say he never returned from a hike.
Just days later, Ms Petito’s body was found at a national park in the US state of Wyoming on September 19.
The coroner recently concluded she died of strangulation and her body had been in the park for up to four weeks.
Search for answers continues
The discovery of Mr Laundrie's remains may have concluded an exhaustive search but the investigation into Ms Petito's death is far from over.
Still, only Brian Laundrie has ever been identified by law enforcement officials as a person of interest in the case.
Laundrie was charged in his absence with unauthorised use of a debit card in late September.
Had he lived, that indictment would have permitted authorities to arrest him.
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